The ways to the trace level analysis in infrared spectroscopy

The future of infrared (IR) spectroscopy as an analytical technique is assured due to its versatility and its numerous advantages; such as the possibility to obtain molecular specific information for virtually any sample in any state with no treatment or minimal sample preparation. However, spectroscopists are not satisfied with relegating IR spectroscopy just to major and minor component analysis and have been looking at analysis at the trace level too. This review is the recognition of the brilliant research performed during the past two decades and the advances achieved in this area, which have made possible the analysis of contaminants at parts per billion (ppb) levels by IR in differen…

A comparative study on sample preparation procedures for supplementary foods by ICP-OES: Green chemistry considerations

An inductively coupled plasma optical emission (ICP-OES) method was developed for the simultaneous determination of major, minor and trace elements in food. Preliminary studies focused on selecting suitable operational conditions in order to provide the highest sensitivity and to maximize the number of analytes to be determined without spectral or matrix interference. Ruthenium and rhenium were evaluated as internal standards and samples were analyzed at different dilution levels. Furthermore, a comparative study was carried out by using three sample digestion methods, microwave-assisted digestion with HNO3/H2O2, dry ashing and dry ashing with Mg(NO3)2/MgO as an ashing aid. Adequate precisi…

Evaluation of the effect of chance correlations on variable selection using Partial Least Squares -Discriminant Analysis

Variable subset selection is often mandatory in high throughput metabolomics and proteomics. However, depending on the variable to sample ratio there is a significant susceptibility of variable selection towards chance correlations. The evaluation of the predictive capabilities of PLSDA models estimated by cross-validation after feature selection provides overly optimistic results if the selection is performed on the entire set and no external validation set is available. In this work, a simulation of the statistical null hypothesis is proposed to test whether the discrimination capability of a PLSDA model after variable selection estimated by cross-validation is statistically higher than t…

Burned bones forensic investigations employing near infrared spectroscopy

The use of near infrared (NIR) spectroscopy was evaluated, by using chemometric tools, for the study of the environmental impact on burned bones. Spectra of internal and external parts of burned bones, together with sediment samples, were treated by Principal Component Analysis and cluster classification as exploratory techniques to select burned bone samples, less affected by environmental processes, to properly carry out forensic studies. Partial Least Square Discriminant Analysis was used to build a model to classify bone samples based on their burning conditions, providing an efficient and accurate method to discern calcined and carbonized bone. Additionally, Partial Least Square regres…

Artificial neural network for quantitative determination of total protein in yogurt by infrared spectrometry

Abstract A method has been introduced for quantitative determination of protein content in yogurt samples based on the characteristic absorbance of protein in 1800–1500 cm− 1 spectral region by mid-FTIR spectroscopy and chemometrics. Successive Projection Algorithm (SPA) wavelength selection procedure, coupled with feed forward Back-Propagation Artificial Neural Network (BP-ANN) model was the benefited chemometric technique. Relative Error of Prediction (REP) in BP-ANN and SPA-BP-ANN methods for training set was 7.25 and 3.70 respectively. Considering the complexity of the sample, the ANN model was found to be reliable, while the proposed method is rapid and simple, without any sample prepa…

Modern trends in solid phase extraction: New sorbent media

Abstract Based on the recently published literature, this review provides an update of the most important features and application of formats and devices employed in solid phase extraction (SPE). Special attention was paid on new trapping media proposed in SPE prior the chromatography analysis, based on the use of nanostructured materials, including carbon nanomaterials, electrospun nanofibers, dendrimes and magnetic nanoparticles, molecular recognition sorbents, as aptamers, immunosorbents, molecular imprinted polymers, ion imprinting polymers, metal-organic frameworks and restricted access materials. Discussions on the present limitations as well as expected future trends of the new trapp…

Atmospheric compensation in Fourier transform infrared (FT-IR) spectra of clinical samples.

A new method is proposed for the elimination of the spectral contribution of two atmospheric gases (CO2 and H2O) in Fourier transform infrared (FT-IR) spectra of clinical samples. The algorithm is based on the measurement of reference spectra of H2O followed by an automatic calculation of the spectral contribution of the above-mentioned gases to the sample spectra. Then this contribution is compensated by spectral subtraction. Attenuated total reflectance FT-IR spectra of serum and urine samples in the presence of atmospheric gases were corrected and compared with spectra obtained with an N2 purge. Visual inspection of the spectra as well as calculated noise levels confirmed that the metho…

Optimization of transmission near infrared spectrometry procedures for quality control of pesticide formulations

The use of different response functions to be optimized in the frame of the use of near infrared spectrometry for quality control of active principles in agrochemical formulations has been evaluated. Both, simple functions, based on parameters like sensitivity, repeatability, accuracy, signal to noise ratio, limit of detection or sample throughput, and a complex function, considering all the aforementioned aspects, were employed in the development of a new method for Iprodione determination in agrochemicals. Optimization strategies were based on the previous screening of the most important instrumental factors like number of cumulated scans, nominal resolution, mirror velocity and zero fill…

Procedures of Separation and Pre‐concentration for Molybdenum Determination Using Atomic Spectrometry—a Review

Abstract The literature concerning the improvement of atomic and ionic procedures for molybdenum determination through separation and pre‐concentration were updated. Analytical procedures based on flame atomic absorption spectrometry (AAAS), electrothermal or graphite furnace atomic absorption spectrometry (GFAAS), inductively coupled plasma optical emission spectrometry (ICP‐OES), and inductively coupled plasma mass spectrometry were reviewed taking into consideration the preliminary steps, which can enhance the selectivity and sensitivity based on co‐precipitation, solvent extraction, and solid‐phase extraction. Both in‐batch and on‐line procedures were considered.

Determination of total mercury in nuts at ultratrace level

Abstract Total mercury, at μg kg−1 level, was determined in different types of nuts (cashew nut, Brazil nuts, almond, pistachio, peanut, walnut) using a direct mercury analyser after previous sample defatting and by cold vapour atomic fluorescence spectrometry. There is not enough sensitivity in the second approach to determine Hg in previously digested samples due to the strong matrix effect. Mercury levels in 25 edible nut samples from Brazil and Spain were found in the range from 0.6 to 2.7 μg kg−1 by using the pyrolysis of sample after the extraction of the nut fat. The accuracy of the proposed method was confirmed by analysing certified reference materials of Coal Fly Ash-NIST SRM 1633…

Mineral Profile of Children’s Fast Food Menu Samples

Abstract Children’s fast food menus, including hamburgers served with french fries, dessert, and a soft drink, were analyzed to obtain the mineral profile of trace elements. The developed analytical methodology involved sample digestion under pressure inside a microwave oven with a mixture of HNO3 and H2O2 and inductively coupled plasma-optical emission spectrometry. The method was validated by carrying out the analysis of certified reference materials (NIST 1570a spinach leaves, NCS ZC73016 chicken, and NIST 1568a rice flour) and using recovery experiments. Repeatability was verified by analyzing replicate samples. Twenty-six elements were studied, 12 of which—aluminum, barium, calcium, co…

Hard cap espresso extraction-stir bar preconcentration of polychlorinated biphenyls in soil and sediments.

Abstract A Nespresso © hard cap espresso machine has been employed for the quantitative extraction of polychlorinated biphenyls (PCBs) from sediments and soils. Sample extraction was performed from five grams of sample in less than 40 s, with 200 mL ethanol 40% (v/v) in water and PCBs were concentrated using stir bar sorptive extraction (SBSE) and determined by thermal desorption-gas chromatography-tandem mass spectrometry (TD-GC-MS-MS). Eleven PCB congeners (28, 52, 77, 80, 81, 101, 118, 138, 153,169, and 180) were determined in soils and sediments with limits of quantification in the 0.03–0.08 ng g −1 range. Extraction efficiency was established by the analysis of soil samples spiked with…

Cutting-edge progress and challenges in stimuli responsive hydrogel microenvironment for success in tissue engineering today.

The field of tissue engineering has numerous potential for modified therapeutic results and has been inspired by enhancements in bioengineering at the recent decades. The techniques of regenerating tissues and assembling functional paradigms that are responsible for repairing, maintaining, and revitalizing lost organs and tissues have affected the entire spectrum of health care studies. Strategies to combine bioactive molecules, biocompatible materials and cells are important for progressing the renewal of damaged tissues. Hydrogels have been utilized as one of the most popular cell substrate/carrier in tissue engineering since previous decades, respect to their potential to retain a 3D str…

Room temperature acid sonication ICP-MS multielemental analysis of milk

Abstract Room temperature acid sonication of milk samples is proposed as a fast alternative methodology for the determination of the total content of 45 elements (Li, Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Rb, Sr, Y, Mo, Ag, Cd, In, Sn, U, Sb, Te, Cs, Ba, Hg, Pb, Bi, Th, La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, Lu, Hf and Ta) in milk by inductively coupled plasma mass spectrometry (ICP-MS). The aforementioned procedure involves a 10 min sample pre-treatment. Measurements were made in quantitative and semiquantitative (Totalquant ® ) modes of analysis using Rh as internal standard and Be, Ge, Tb and Re for internal calibration of the equipment in the semiquantitative mode. The…

On-line sample treatment and FT-IR determination of doxylamine succinate in pharmaceuticals

Abstract A low solvent consumption method for Fourier transform infrared spectroscopy (FT-IR) determination of doxylamine succinate in pharmaceuticals has been developed. The analyte was continuous and selectively extracted with a 13% (v/v) ethanol:chloroform solvent mixture, recirculating the solvent through the sample and monitoring the process by FT-IR. Doxylamine succinate was determined by on-line standard addition measuring the peak area in the regions 1730–1710 and 1485–1462 cm −1 corrected with a two-point baseline established between 2000 and 1800 cm −1 . This new method implies low volumes of chloroformic solvent mixture, only 2.6 mL per sample, in front of classical batch FT-IR m…

Teaching Green Analytical and Synthesis Chemistry: Performing Laboratory Experiments in a Greener Way

Our future challenges in resource, environmental and societal sustainability demand efficient and benign-by-design scientific technologies for working with chemical processes and products. In this chapter, we have considered the major aspects of green analytical and synthetic chemistry as a new paradigm and its integration with higher education course curriculum. Teaching green analytical chemistry must be focused on analytical parameters and practices more than on the incorporation of the so-called green parameters to the basic analytical properties. Thus accuracy, representativeness, traceability, sensitivity and selectivity in the renewed paradigmatic chemistry have been complemented and…

FTIR determination of Aspartame and Acesulfame-K in tabletop sweeteners.

Two different strategies for sweeteners determination in tabletop samples by Fourier transform middle-infrared (FTIR) spectrometry, an off-line and a fully mechanized extraction of Aspartame and Acesulfame-K with different mixtures of chloroform and methanol, have been developed. The off-line method involves the extraction of both active principles by sonication of samples with 25:75 v/v CHCl3/CH3OH and direct measurement of the peak height values at 1751 cm(-1), corrected using a baseline defined at 1850 cm(-1) for Aspartame, and measurement of the peak height at 1170 cm(-1) in the first-order derivative spectra, corrected by using a horizontal baseline established at 1850 cm(-1), for Aces…

An Infrared Method, with Reduced Solvent Consumption, for the Determination of Chlorsulfuron in Pesticide Formulations

A simple method has been developed for the determination of Chlorsulfuron in pesticide formulations by Fourier Transform Infrared (FTIR). Samples were diluted with CHCl3− , and the FTIR spectra of the samples and standards were obtained at a nominal resolution of 4 cm− 1 from 4000 to 900 cm− 1 with the accumulation of 25 scans. Chlorsulfuron determination was based on the measurement of peak area values from 1373 to 1363 cm− 1 which were corrected by use of a two points baseline defined from 1401 to 1302 cm− 1. The limit of detection achieved, which was of the order of 6 µg g− 1, was appropriate for the determination of Chlorsulfuron in commercially available formulations. FTIR results were…

Determination of indoor air quality of a phytosanitary plant.

A new methodology has been developed to determine volatile organic compounds (VOCs) and pesticides in ambient air using membrane based devices as passive samplers. Pesticides were determined by gas chromatography with mass spectrometry detection (GC-MS) after their microwave-assisted extraction (MAE) from the passive sampler and the required clean-up. On the other hand, VOCs were also caught with the same samplers and directly determined by head space (HS) coupled to GC-MS. The use of samplers filled with florisil and activated carbon allows us to catch with a simple device both, VOCs and pesticides, with a high vapor pressure. Results obtained in the deployment of samplers in different sit…

An infrared spectroscopic tool for process monitoring: sugar contents during the production of a depilatory formulation.

Abstract A fast, reliable and economical methodology has been developed to control the production process of sugar-based depilatories. The method is based on the use of attenuated total reflectance—Fourier transform infrared (ATR-FTIR) spectroscopy in combination with multivariate data analysis. A very simple sample preparation process involving the dissolution of samples in water was applied. Employing a multivariate calibration model established from data of 15 well characterized samples, prediction errors equal or below 3.04 mg mL−1 for the quantitative determination of fructose, glucose, sucrose, maltose and maltotriose were obtained. Results found in this preliminary study indicate a g…

Flavonoid determination in onion, chili and leek by hard cap espresso extraction and liquid chromatography with diode array detection

Abstract A low cost extraction procedure, based on the use of a hard cap espresso machine, has been developed for the extraction of myricetin, quercetin, luteolin and kaempferol from vegetables by using 50 mL of ethanol in water (80% v/v) in

Application of infrared spectroscopy as Process Analytics Technology (PAT) approach in biodiesel production process utilizing Multivariate Curve Resolution Alternative Least Square (MCR-ALS)

Abstract Process Analytical Technology means at-line collection of analytical information from the process when the reaction is in progress. Obtained information enables process engineers to better control the Critical Process Parameters and direct the reaction to desirable routs. Near-infrared spectroscopy due to its analytical features, as well as the high capability of automation, versatile sampling and spectral acquisition methods is a useful tool in process monitoring when coupled to chemometrics. The Multiple Scatter Correction preprocessing technique and Alternative Least Square method can extract spectral and concentration information of a reaction mixture simultaneously, were emplo…

Biodegradable nano-polymers as delivery vehicles for therapeutic small non-coding ribonucleic acids.

Nowadays, small non-coding Ribo Nucleic Acids (sncRNAs) such as siRNA, miRNA and shRNA are extremely serving to gene regulation. They are involved in many biological processes and in an increasing number of studies regarding a variety of application of sncRNAs toward human health and relieving diseases ranging from metabolic disorders to those involving various organ systems as well as different types of cancer. One of the most severe limitations for applying RNA interference technology is the absence of safe and effective carriers for in vivo delivery, including localizing the molecules to a specific site of interest and sustaining the presentation of the payloads for a controlled period o…

Hydrogel‐Based 3D Bioprinting for Bone and Cartilage Tissue Engineering

As a milestone in soft and hard tissue engineering, a precise control over the micropatterns of scaffolds has lightened new opportunities for the recapitulation of native body organs through three dimentional (3D) bioprinting approaches. Well-printable bioinks are prerequisites for the bioprinting of tissues/organs where hydrogels play a critical role. Despite the outstanding developments in 3D engineered microstructures, current printer devices suffer from the risk of exposing loaded living agents to mechanical (nozzle-based) and thermal (nozzle-free) stresses. Thus, tuning the rheological, physical, and mechanical properties of hydrogels is a promising solution to address these issues. Th…

Mesoporous silica-based materials for use in biosensors

Abstract There have been great advancements in the development of biosensors capable of characterizing and quantifying biomolecules. This article gives an overview of the formation, the properties and the electrochemical applications of ordered mesoporous silica-based materials in electrocatalysis, electrosorption, matrix immobilization, construction of systems for controlled release of active compounds, sensors, biosensors and immunosensors. We also present a comprehensive overview of current developments and key issues in the determination of some biological molecules with particular emphasis on the evaluation of models.

The Concept of Green Analytical Chemistry

Three years ago, when we published our review paper on Green Analytical Chemistry [1] it was clear that, at this time, Green Chemistry was a well established paradigm well supported by more than 50 published books, an increasing number of research teams who influenced the scientific literature and involved the editions of special journals like

Baby foods

Non-chromatographic speciation analysis of arsenic and antimony in milk hydride generation atomic fluorescence spectrometry

Abstract A rapid, high sensitivity method has been developed for the determination of As(III), As(V), Sb(III) and Sb(V) in milk samples by using hydride generation atomic fluorescence spectrometry. The method is based on the leaching of As and Sb from milk through the sonication of samples with aqua regia followed by direct determination of the corresponding hydrides both before and after reduction with KI. It was confirmed by recovery experiments on spiked commercially available samples that neither the reduced nor the oxidized forms of the elements under study or mixtures of the two oxidation states were modified by the room temperature sample treatment with aqua regia. The methodologies …

On-line speciation of mercury in fish by cold vapour atomic fluorescence through ultrasound-assisted extraction

A fully mechanized procedure has been developed for the speciation of mercury in fish samples by using cold vapour atomic fluorescence spectrometry (CV-AFS). Sample slurries in an acid mixture in the presence of a surfactant and with traces of K2Cr2O7, were injected into a flow system, sonicated and merged with 1 ml of an oxidant mixture of KBr/KBrO3 heated at 50 °C in a water bath and total Hg determined by CV-AFS. Sonicated sample slurries were also measured, in the absence of KBr/KBrO3, in order to obtain a second series of data which could be employed to establish the concentrations of free Hg(II). Different compositions of the acidic extractant solutions were evaluated by mixing HCl, H…

Green Chemistry in Higher Education: State of the Art, Challenges, and Future Trends

Nowadays, there is increasing interest in global sustainability, and thus, university students would like to know how human actions affect the health status of our planet. This is mainly due to their basic knowledge of problems such as global warming and greenhouse gases. Students would like to gain knowledge on how to safeguard the earth for future generations. This must involve changes in education programs at interested institutions and universities. To ensure that future generations of chemists are equipped with proper knowledge, significant efforts are needed. Thus, this article aims to present the history of green chemistry, its milestones, and ideas on how to teach this subject. A di…

A nondestructive intelligent approach to real‐time evaluation of chicken meat freshness based on computer vision technique

In this study, the capability of a procedure based on combination of computer vision (CV) and artificial intelligence techniques examined for intelligent and nondestructive prediction of chicken meat freshness during the spoilage process at 4°C. The proposed system comprises the following stages: capture images, image preprocessing, image processing, computing channels, feature extraction, feature selection by a hybrid of genetic algorithm (GA) and artificial neuronal network (ANN), and prediction by using ANN. The number of neurons in input layer was determined 33 (selected features) and freshness used as the output. The ideal ANN model was obtained with 33‐10‐1 topology. The high performa…

Indirect chronology method employing rare earth elements to identify Sagunto Castle mortar construction periods

A novel indirect chronology method has been developed to identify Sagunto Castle construction periods. The method is based on the use of inductively coupled plasma mass spectrometry (ICP-MS) to determine rare earth elements (REE) and other trace elements in mortars. Additionally, a no destructive geochemical analysis based on X-ray fluorescence (XRF) was employed for major elements determination. Collected chemical data were processed through Principal Component Analysis (PCA) to highlight any differences among the mortars belonging to different buildings and construction periods. The results show that PCA analysis permits to discriminate construction periods according to mortar sample REE …

Modelling of the ternary system H3PO4/H2O/TBP

Abstract A thermodynamic model is presented for the extraction of phosphoric acid from water by tri-n-butylphosphate (TBP), from aqueous solutions containing 0–6 mol/kg phosphoric acid. The activity coefficient of phosphoric acid was calculated from experimental data using Pitzer’s equation, and those of the components in the organic phase were calculated by Sergievskii–Danus’s relationship. The proposed model gives a satisfactory description of the distribution of phosphoric acid and water, in the considered concentration range, by taking into account the formation of the following species: TBP, TBP·H2O, H3PO4·TBP and (TBP)2·H3PO4·H2O.

Mineral profile of kaki fruits (Diospyros kaki L.)

The main objective of this study was the determination of the mineral profile of 167 kaki fruit (Diospyros kaki L.) samples produced from different regions of Spain, including samples with the protected designation of origin (PDO) 'Kaki Ribera del Xúquer' Valencia (Spain). Samples were analysed by inductively coupled plasma optical emission spectroscopy (ICP-OES) and inductively coupled plasma mass spectrometry (ICP-MS). Consumption of one piece of kaki fruit (200-400 g) would give a mineral intake providing 1-10% of the recommended daily allowance (RDA) for calcium, 1-30% for copper and potassium, 1-15% from iron and magnesium, up to 1% of sodium, and up to 4% of zinc. ANOVA analysis indic…

Aptamers as smart ligands for nano-carriers targeting

The development of enhanced drug delivery systems is one of the most attractive fields of pharmaceutical sciences, as some of the highly effective chemo/biotherapeutics for cancer treatment can not be administrated due to their high toxicities for normal cells or low stability in physiological media. However, drugs that are currently not administrable will become valuable if specific cell-targeted drug carriers can protect the normal cells from adverse effects and also improve drug pharmacokinetics. Aptamers are attractive and promising biomaterials developed with high affinity and specificity against numerous valuable targets. They could act similar to monoclonal antibodies (mAbs), and off…

Flow Injection Fourier Transform Infrared Determination of Caffeine in Soft Drinks

A fully automated procedure has been developed for FT-IR determination of caffeine in soft drinks. Samples are first degasified by filtration and then directly injected into a flow manifold and passed through a 100 mg C18 SPE cartridge, conditioned with methanol and water. After the cartridge has been cleaned with water, the caffeine is eluted with CHCl3 and stabilized with ethanol. The flow injection (FI) recording is obtained by measuring the absorbance at 1658 cm-1 with a baseline established at 1800 cm-1. Area values for the FI recording obtained between 0.4 and 1.4 min after sample injection are interpolated in the calibration graph of a series of aqueous standards of caffeine, which w…

Green chromatography for the analysis of foods of animal origin

Abstract The use of green chromatography methods, for the determination of different components and contaminants in foods of animal origin, has been reviewed from a literature update of papers published in the last years, paying special attention to the efforts regarding the reduction and greening of the sample preparatory steps, the use of clean alternative mobile phases, the improvement of stationary phases used in this type of analysis, and the increase of the analytical information obtained from each chromatography run. In general, it can be seen that the efforts to reduce the deleterious side effects of the analytical methods have also been focused on the maintenance, or improvement, o…

Altered elemental profile as indicator of homeostatic imbalance in pathogenesis of oral submucous fibrosis

Oral submucous fibrosis (OSF) is a potential precancerous condition of the oral cavity and oropharynx. The etiopathogenesis of this complex precancerous condition is still obscure. In addition to deleterious oral habits, malnutrition, and possible genetic predisposition, altered bioelemental status is also likely to play an important role in its pathogenesis. The present study analyzed 68 elements by inductively coupled plasma-mass spectroscopy in oral mucosa of normal and OSF individuals and some interesting alterations in elemental profile in the diseased tissue have been noted, indicating a homeostatic imbalance. These bioelemental alterations leading to homeostatic imbalance might be co…

Speciation of selenium and tellurium in milk by hydride generation atomic fluorescence spectrometry

A simple, fast and highly sensitive method has been developed for the differentiation of Se and Te into their (IV) and (VI) oxidation states in milk samples by HG-AFS. This procedure involves a previous leaching of milk slurries by sonication with aqua regia for 10 min. Se(IV) and Te(IV) were determined by analysis of the samples without a pre-reduction step; being total Se and Te determined after reduction with KBr. The method provides limit of detection values (LOD) of 0.012 and 0.023 ng ml−1 for Se(IV) and Te(IV) respectively. Average relative standard deviation values of 10.5%, 3.9%, 12% and 12.5% were found for the determination of Se(IV), Se(VI), Te(IV) and Te(VI) in milk samples cont…

Implementing the contamination prevention programs in the pesticide industry by infrared spectroscopy.

Abstract An infrared spectroscopy based methodology has been successfully developed to implement contamination prevention programs in the pesticide industry. Sensitivity of the IR procedure, traditionally considered the Achilles Hell of the technique, has been improved by using a transmission cell with an open upper side, an internal volume of 35 µL and an optical pathlength of 0.5 mm, providing detection limits of 32 mg L−1 for folpet and 48 mg L−1 for cymoxanil. The manufacturing of folpet and cymoxanil was employed as an example and the IR methodology was validated for the implementation of contamination prevention programs in the pesticide industry. The swab test and rinsate method were…

Micropumping multicommutation turbidimetric analysis of waters

Abstract A micropumping multicommutation manifold to perform turbidity determinations in waters is described. The procedure is based on the use of a combination of hydrazine sulfate and hexamethylenetetramine, to obtain an external standard of nephelometric turbidity units (NTU), which could compare the absorbance measurements at high wavelengths for samples with a calibration line obtained from a concentrated formazine standard diluted on-line. To minimize sample and reagent consumption and waste generation, the flow system was designed with two solenoid micro-pumps, one of them for the alternative introduction of the formazine standard and samples and the other one for the water carrier. …

Recent advancements in structural improvements of lateral flow assays towards point-of-care testing

Abstract Lateral flow assays (LFAs) provide some of the most attractive point-of-care instruments for broad applications with simple, rapid, user-friendly, and cost-effective characteristics. However, these technologies suffer from low sensitivity, the poor limit of detection, and just qualitative or semi-quantitative results that restrict their practical applications. Extensive research has been reported in this area involving sensitivity enhancement, multiplex analysis, the implementation for broad analytes, and development of novel electronic readers for quantitative analysis. This review presents recently reported works for the structural improvements of LFAs considering antibody immobi…

The role of green extraction techniques in Green Analytical Chemistry

Abstract Greening extraction techniques to improve the sensitivity and the selectivity of analytical methods is the sustainable alternative to classical sample-preparation procedures used in the past. In this update, we review the main strategies employed in the scientific literature to reduce deleterious side-effects of extraction techniques. We demonstrate that the evolution of sample-treatment procedures is focused on the simultaneous improvement of the main analytical features of the method and its practical aspects, including the economic case.

Quality control of Metamitron in agrochemicals using Fourier transform infrared spectroscopy in the middle and near range

Abstract Two vibrational spectrometry-based methodologies were developed for Metamitron determination in pesticide formulations. Fourier transform-middle infrared (FT-MIR) procedure was based on the extraction of Metamitron by CHCl 3 and latter determination by peak area measurement between 1556 and 1533 cm −1 , corrected with a two points baseline established from 1572 to 1514 cm −1 . Fourier transform-near infrared (FT-NIR) determination was made after the extraction of Metamitron in acetonitrile and measuring the peak area between 6434 and 6394 cm −1 corrected using a two points baseline defined between 6555 and 6228 cm −1 . Repeatability, as relative standard deviation, of 5 independent…

Quantification of phenolic acids by partial least squares Fourier-transform infrared (PLS-FTIR) in extracts of medicinal plants.

Introduction Phenolic compounds are ubiquitous compounds found in all plants as their secondary metabolites. Phenols are becoming increasingly important particularly because of their beneficial effects on health. Objective To provide a faithful calibration model for the simultaneous determination and quantification of phenolic acids, as salicylic, vanillic, p-hydroxybenzoic acids, eugenol and thymol in different extracts of medicinal plants, a comparative study was made between two methods of infrared measurements based on attenuated total reflectance (ATR) and transmission. Methods Characteristic absorbance peak heights of mid-infrared spectra of individual phenolic acids were measured for…

Chemometric extraction of analyte-specific chromatograms in on-line gradient LC-infrared spectrometry

This work exploits the possibilities offered by the recently developed multivariate method named Science-Based Calibration (SBC), for the extraction of ‘analyte-specific’ chromatograms in on-line gradient reversed phase LC-infrared spectrometry (IR) in the presence of a high spectral and chromatographic overlapping between the analyte of interest, co-eluting sample matrix constituents and the mobile phase components. The SBC method uses an experimentally measured single response spectrum of the analyte of interest and representative noise to calculate an optimum regression vector (bopt(1)). Then, the bopt(1) vector is used to predict the concentration of the analyte of interest in the spect…

Near infrared determination of Diuron in pesticide formulations

Abstract A simple, fast and environmentally friendly near infrared (NIR)-based methodology was developed for Diuron determination in pesticide formulations. This methodology was based on the pesticide extraction with acetonitrile and subsequent transmittance measurement determination by peak area measurement between 2021 and 2047 nm, corrected with a single point baseline established at 2071 nm. The repeatability, as relative standard deviation of five independent analysis of a 15.3 mg g −1 Diuron standard was 0.03% and the limit of detection 0.013 mg g −1 . The reagent consumption was clearly reduced in front of a chromatographic reference procedure from 39.1 ml acetonitrile per sample, re…

Editorial overview: Green analytical chemistry

International audience

Biosensing of microcystins in water samples; recent advances

Safety and quality of water are significant matters for agriculture, animals and human health. Microcystins, as secondary metabolite of cyanobacteria (blue-green algae) and cyclic heptapeptide cyanotoxin, are one of the main marine toxins in continental aquatic ecosystems. More than 100 microcystins have been identified, of which MC-LR is the most important type due to its high toxicity and common detection in the environment. Climate change is an impressive factor with effects on cyanobacterial blooms as source of microcystins. The presence of this cyanotoxin in freshwater, drinking water, water reservoir supplies and food (vegetable, fish and shellfish) has created a common phenomenon in …

Lateral flow assays towards point-of-care cancer detection: A review of current progress and future trends

Abstract Cancer is one of the main causes of mortality and morbidity worldwide. However, its early non-invasive detection via quantification of appropriate biomarkers can significantly reduce mortality, enhance survival, and save treatment costs. Lateral flow test strips (LFTS) are nowadays considered as the most attractive point-of-care devices for healthcare applications. However, the quantification of cancer biomarkers in body fluids suffers from some challenges including i) the necessity for multiplex analysis, ii) the development of sensitive detection systems, iii) to overcome the analysis of complex samples, at the same time, it should keep the quality assurance criteria for an accur…

Prediction of banana quality indices from color features using support vector regression

Banana undergoes significant quality indices and color transformations during shelf-life process, which in turn affect important chemical and physical characteristics for the organoleptic quality of banana. A computer vision system was implemented in order to evaluate color of banana in RGB, L*a*b* and HSV color spaces, and changes in color features of banana during shelf-life were employed for the quantitative prediction of quality indices. The radial basis function (RBF) was applied as the kernel function of support vector regression (SVR) and the color features, in different color spaces, were selected as the inputs of the model, being determined total soluble solids, pH, titratable acid…

A chemiluminescence flow-based procedure for determination of carbaryl in natural waters exploiting multicommutation and enzymatic reaction

A chemiluminescence procedure for the determination of carbaryl in natural waters using acetylcholinesterase and choline oxidase is described. The flow system designed to implement multicommutation approach controlled by microcomputer comprised five solenoid valves, two columns with immobilized enzymes on controlled pore glass beads and chemiluminometric flow cell. In the best experimental conditions a linear response ranging from 25 to 700 µg L-1 carbaryl was obtained. Water samples were spiked with carbaryl in order to access the accuracy and recoveries between 95 and 101% were obtained for a concentration level ranging from 25 to 100 µg L-1 carbaryl. Detection limit and variation coeffic…

Determination of As, Sb, Se, Te and Bi in milk by slurry sampling hydride generation atomic fluorescence spectrometry

A simple and fast analytical procedure has been developed for the determination of As, Sb, Se, Te and Bi in milk samples by hydride generation atomic fluorescence spectrometry (HG-AFS). Samples were treated with aqua regia for 10min in an ultrasound water bath and pre-reduced with KBr for total Se and Te determination or with KI and ascorbic acid for total As and Sb, the determination of Bi being possible in all with or without pre-reduction. Slurries of samples, in the presence of antifoam A, were treated with NaBH(4) in HCl medium to obtain the corresponding hydrides, and AFS measurements were processed in front of external calibrations prepared and measured in the same way as samples. Re…

Fourier-transform infrared determination of nicotine in tobacco samples by transmittance measurements after leaching with CHCl3

Abstract A new procedure is proposed for the FT-IR spectrometric determination of nicotine in tobacco. The method is based on the extraction of nicotine in CHCl 3 from tobacco samples, wetted with an aqueous solution of NH 3 (0.1 M), and the measurement of absorbance in the stopped-flow mode at 1316 cm −1 , using a spectral baseline correction established from 1334 to 1300 cm −1 . The procedure developed does not requires a complex sample preparation, and provides a limit of detection of 0.045 mg ml −1 nicotine, a sampling frequency of 3.3 h −1 and a coefficient of variation of 0.3% for five independent measurements of a tobacco sample with a nicotine content of 1.5% w/w. The accuracy of th…

Applications of diatoms and silica nanotechnology in biosensing, drug and gene delivery, and formation of complex metal nanostructures

Abstract Diatoms, single-cell eukaryotic microalgae, are present in nearly every water habitat and their silicon-dioxide (silica)-based cell walls of tens to hundreds of micrometers in size are the most interesting feature to be used in nanotechnology, including biosensing, drug delivery, molecular separation, molecular biology, biomimetics, frustule formation, and electronic, photonic, optical and structural materials. In this review, we present recent progress in applications of diatoms and silica nanomaterials in biosensing, drug and gene delivery, and formation of complex metal nanostructures.

Photochemical Size Reduction of CdSe and CdSe/ZnS Semiconductor Nanoparticles Assisted by nπ* Aromatic Ketones

A novel effect of n pi* aromatic ketones on the quantum dots optical properties is reported. By controlling experimental conditions such as time of irradiation, presence of air in the media, hydrogen donor capacity of the solvent, and irradiation wavelength, core and core-shell CdSe QDs can be resized as convenient.

Tips on ligand immobilization and kinetic study using surface plasmon resonance.

Surface plasmon resonance (SPR) technique offers a robust label-free approach applicable in various investigations including binding affinity, specificity and kinetics of biological macromolecules (e.g., peptides, proteins and nucleotidase) and small molecules. SPR provides extremely important data on the kinetics and affinity of substances examined, through which bio-specific interaction(s) can be established by the analysis of adsorption of analyte onto the immobilized ligand(s) on a sensor-based analytical system. Due to SPR wide applications in biomedical laboratories, the aim of this editorial is to highlight the importance of SPR in affinity kinetics and ligand immobilization.

Carbon based nanomaterials for tissue engineering of bone: Building new bone on small black scaffolds: A review.

Graphical abstract

Determination of inorganic species of Sb and Te in cereals by hydride generation atomic fluorescence spectrometry

A non-chromatographic fast, sensitive and easy method has been developed for the determination of Sb(III), Sb(V), Te(IV) and Te(VI) in cereal samples. The procedure is based on ultrasound assisted extraction and determination by hydride generation atomic fluorescence spectrometry (HG AFS). Preliminary studies were made in order to get the best extraction efficiency using 1 mol L-1 phosphoric acid, 1 mol L-1 nitric acid, aqua regia, 1 mol L-1 sulfuric acid and 6 mol L-1 hydrochloric acid. The extraction with aquaregia showed a clear interconversion of the species during the process, being H2SO4 the best extractant with efficiencies greater than 90% from the total content of Sb and Te quantif…

Nanomaterial-based biosensors for detection of pathogenic virus

Viruses are real menace to human safety that cause devastating viral disease. The high prevalence of these diseases is due to improper detecting tools. Therefore, there is a remarkable demand to identify viruses in a fast, selective and accurate way. Several biosensors have been designed and commercialized for detection of pathogenic viruses. However, they present many challenges. Nanotechnology overcomes these challenges and performs direct detection of molecular targets in real time. In this overview, studies concerning nanotechnology-based biosensors for pathogenic virus detection have been summarized, paying special attention to biosensors based on graphene oxide, silica, carbon nanotub…

Fast extraction methodologies for the determination of toxic arsenic in meat

Summary A nonchromatographic analytical procedure has been developed for the determination of arsenic in meat samples including the major toxic arsenic species arsenite, arsenate, monomethylarsonic acid (MMA) and dimetylarsinic acid (DMA). The method is based on the extraction of arsenic species in mild conditions, selective trivalent hydride formation and final determination by hydride generation atomic fluorescence spectroscopy (HG-AFS). Different extractant agents and two different procedures, microwave-assisted extraction (MAE) and ultrasound assisted extraction at room temperature, were evaluated for As species extraction. The method provided a limit of detection of 0.013 ng mL−1 and a…

Dynamic reaction cell inductively couple plasma-mass spectrometry optimization for seawater analysis

Abstract A direct method for dynamic reaction cell inductively coupled plasma- mass spectrometry (DRC-ICP-MS) trace mineral elements determination in seawater was optimized by Experimental Statistical Design. Five instrumental parameters, such as radiofrequency, sample, nebulizer and reaction gas flows, rejection parameter q and axial field voltage were studied. A Plackett-Burman design was used for screening the most important parameters and the most significant ones were optimized with a Central composite design. Fifteen elements and different isotopes for some of these were considered through the study. The optimization was achieved by using three different reaction gases (NH3, CH4 and O…

Comparison of two vibrational procedures for the direct determination of mancozeb in agrochemicals.

The direct determination of mancozeb in agrochemicals has been made by diamond attenuated total reflectance (ATR) Fourier transform infrared spectroscopy in the middle range (DATR-MIR) and diffuse reflectance infrared Fourier transform spectroscopy in the near range (DR-NIR) methods using in both cases a previous identification of the samples using a dendrographic classification and an appropriate partial least squares (PLS) calibration established from a set of nine external standards and optimized for each type of sample. It was analyzed a heterogeneous population of 11 samples obtained from the Spanish market, containing different co-formulated products, such as fosetyl-Al, copper oxychl…

Regional provenance of dolerite prehistoric objects through mineral analysis

Abstract A methodology based on the mineral analysis determination has been developed to identify the origin of dolerite stone outcrops collected to fabricate lithic objects during the Prehistoric period. The method is based on the use of inductively coupled plasma mass spectrometry (ICP-MS) to analyse rare earth elements (REE) and trace elements. Additionally a no destructive geochemical analysis based on X-ray fluorescence (XRF) was employed for major elements analysis. The aforementioned methodologies were applied to samples from different archaeological fields or natural outcrops located in the Mediterranean area of Spain, between Valencia and Alicante. Principal component analysis (PCA…

Nutritional parameters of commercially available milk samples by FTIR and chemometric techniques

Abstract A chemometric study on the prediction of the main nutritional aspects of milk has been carried out by using fourier transform infrared spectroscopy (FTIR) attenuated total reflectance (ATR) measurements of commercially available milk samples of different types. Whole, semi and skimmed milks, enriched or not with calcium, vitamins or modified by alteration of lipid or sugar composition were considered. After evaluating different strategies for data acquisition and ATR cleaning between samples, hierarchical cluster analysis (HCA) was carried out for classification of samples in order to choose the calibration set. The prediction capabilities of partial least squares (PLS) data treatm…

The use of quantum dots in organic chemistry

Abstract We discuss the main mechanisms of interaction between quantum dots (QDs) of different types and organic molecules within the framework of the use of photo-physical properties of colloidal semiconductor nanoparticles for sensing organic and biochemical compounds. We reviewed the recent literature in the field to provide a picture of the state of the art of our knowledge and perspectives on this challenging field. Bearing in mind analysis in organic chemistry based on luminescence and electrochemical changes, we discuss surface interaction based on the use of QDs capped with thiol, cystein, citrate, surfactant, purine and nitroxides, and we explain ligand-analyte, bioconjugate-analyt…

In situ derivatization for double confirmation of 2C–C in oral fluids by ion mobility spectrometry

Ion mobility spectrometry (IMS) is a powerful tool to carry out quick and sensitive detection of illicit activities and has been employed for the determination of the psychedelic drug 2,5-dimethoxy-4 chlorophenethylamine (2C–C) in oral fluid samples. Saliva samples were extracted with chloroform and analysed by IMS reaching a limit of detection (LOD) of 14 μg L−1. Nevertheless, IMS has a scarce resolution and selectivity of the method can be often compromised by the presence of potential interferents with similar molecular weights and drift times. Thus, a rapid and in situ derivatization with acetone, to form the corresponding imine, has been proposed in the present study to confirm the pre…

Green strategies for decontamination of analytical wastes

Within the paradigm of green analytical chemistry, we discuss the different options for cleaning analytical wastes in the literature, paying special attention to on-line recycling of solvents, degradation of toxic compounds and trace-element passivation. The objective of this review is to present and to evaluate critically suitable methodologies that can be incorporated into analytical methods in order to reduce or to avoid the generation of toxic wastes, which could cumulate in the laboratory and have to be managed outside, so increasing the risks and the cost of analysis.

Preparation of Carbon-14 Labeled 2-(2-mercaptoacetamido)-3-phenylpropanoic Acid as Metallo-beta-lactamases Inhibitor (MBLI), for Coadministration with Beta-lactam Antibiotics.

Aim and Objective: Bacteria could become resistant to β-lactam antibiotics through production of β- lactamase enzymes like metallo-β-lactamase. 2-(2-mercaptoacetamido)-3-phenylpropanoic acid was reported as a model inhibitor for this enzyme. In order to elucidate the mechanism of action in the body’s internal environment, preparation of a labeled version of 2-(2-mercaptoacetamido)-3-phenylpropanoic acid finds importance. In this regard, we report a convenient synthetic pathway for preparation of carbon-14 labeled 2-(2- mercaptoacetamido)-3-phenylpropanoic acid. Materials and Methods: This study was initiated by using non-radioactive materials. Then, necessary characterization was performed…

Testing of the region of Murcia soils by near infrared diffuse reflectance spectroscopy and chemometrics.

A partial least squares near infrared (PLS-NIR) method has been developed for the determination of several physicochemical parameters in soils from different locations of the Region of Murcia. The method was based on the proper chemometric treatment of diffuse reflectance spectra of soil samples. Reflectance spectra were scanned from samples stored in glass vials in the NIR region between 800 and 2600 nm, averaging 36 scans per spectrum at a resolution of 8 cm(-1). Models were built using reference data of 39 samples selected from a dendrogram obtained after hierarchical cluster analysis of NIR spectra of soils and prediction parameters were established from a validation set of 109 addition…

Spectrophotometric flow injection determination of formetanate and m-aminophenol in water after reaction with p-aminophenol

Abstract An automated procedure has been developed for the determination of formetanate and its metabolite m -aminophenol (MAP) in water samples. MAP can be selectively determined in the presence of formetanate by direct on-line reaction with p -aminophenol and spectrophotometric measurement of the absorbance at 576 nm in the presence of KIO 4 , as oxidizing agent. The method has a limit of detection of 5 × 10 −7 M , it provides a recovery percentage from 95 to 104% and permits one to carry out 120 measurements/hr. The spectrophotometric determination of formetanate must be carried out after a previous hydrolysis to MAP. To determine formetanate in the presence of MAP, two steps are necessa…

Sample preparation strategies for the determination of psychoactive substances in biological fluids

This review focuses on the existing analytical procedures for the determination of new psychoactive substances (NPS) in biological fluids by chromatographic methods. Direct analysis of samples is scarcely employed and most proposed methodologies include a sample pre-treatment in order to remove matrix interferents and, in some cases, pre-concentrate extracts. Current extraction methods for NPS determination in plasma/serum, urine, and oral fluids have been widely discussed, such as liquid-liquid, solid-phase, and micro extraction approaches, highlighting the advantages and drawbacks of the proposed extraction methodologies. Regarding microextraction approaches, techniques like microextracti…

A fast and simple spectrofluorometric method for the determination of alendronate sodium in pharmaceuticals

Introduction: Alendronate sodium enhances bone formation and increases osteoblast proliferation and maturation and leads to the inhibition of osteoblast apoptosis. Therefore, a rapid and simple spectrofluorometric method has been developed and validated for the quantitative determination of it. Methods: The procedure is based on the reaction of primary amino group of alendronate with o-phthalaldehyde (OPA) in sodium hydroxide solution. Results: The calibration graph was linear over the concentration range of 0.0-2.4 μM and limit of detection and limit of quantification of the method was 8.89 and 29 nanomolar, respectively. The enthalpy and entropy of the reaction between alendronate sodium …

Partial least squares X-ray fluorescence determination of trace elements in sediments from the estuary of Nerbioi-Ibaizabal River.

The feasibility of partial least squares (PLS) regression modeling of X-ray fluorescence (XRF) spectra of estuarine sediments has been evaluated as a tool for rapid trace element content monitoring. Multivariate PLS calibration models were developed to predict the concentration of Al, As, Cd, Co, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Sn, V and Zn in sediments collected from different locations across the estuary of the Nerbioi-Ibaizabal River (Metropolitan Bilbao, Bay of Biscay, Basque Country). The study was carried out on a set of 116 sediment samples, previously lyophilized and sieved with a particle size lower than 63 microm. Sample reference data were obtained by inductively coupled plasma mass …

Molecular beacon strategies for sensing purpose

Abstract The improvement of nucleic acid probes as vital molecular engineering devices will cause a noteworthy contribution to developments in bioimaging, biosensing, and disorders diagnosis. The molecular beacon (MB) which was designed by Tyagi and Kramer in 1996, are loop-stem hairpin-designed oligonucleotides armed with a quencher and a dye (also named reporter groups) at the 3′ or 5′ ends. This construction allows that MBs in the absence of their target complementary molecules do not fluoresce. Through hybridization with their specific targets a spontaneous configuration change on MBs occur and the dye and quencher separate from each other, resulting in emitting the fluorescence. MBs ar…

On-line vapor-phase generation combined with Fourier transform infrared spectrometry

We present a critical review of on-line vapor-phase generation combined with Fourier transform infrared spectrometry for detection. We discuss different experimental approaches developed for generating the vapor phase based on different principles (e.g., thermal volatilization, acid-base, redox reaction and covalent hydride generation). Using examples of applications, we try to demonstrate the analytical potential of on-line vapor-phase generation in vibrational spectrometry in order to improve the selectivity and the sensitivity of the measurement step and to make environmentally-friendly procedures available for problem solving in the analytical laboratory. We pay special attention to int…

Preliminary results on direct quantitative determination of cocaine in impregnated materials by infrared spectroscopy

Abstract Partial least squares models were built for the direct determination of cocaine in seized impregnated smuggled materials. Measurements are based on the attenuated total reflectance middle infrared spectra (ATR-MIR) and diffuse reflectance spectra in the near range (DR-NIR) obtained directly from the surface of the impregnated materials. The aforementioned procedures offer fast, cheap and environmentally friendly green alternatives to the reference method based on the extraction of the drug and its quantification by gas chromatography. Additionally it has been verified that results found are statistically comparable with those obtained by the reference method with root mean square e…

Strategies in DNA vaccine for melanoma cancer

According to reports of the international agency for cancer on research, although malignant melanoma shows less prevalence than nonmelanoma skin cancers, it is the major cause of skin cancer mortality. Given that, the production of effective vaccines to control melanoma is eminently required. In this regard, DNA-based vaccines have been extensively investigated for melanoma therapy. DNA vaccines are capable of inducing both cellular and humoral branches of immune responses. These vaccines possess some valuable advantages such as lack of severe side effects and high stability compared to conventional vaccination methods. The ongoing studies are focused on novel strategies in the development …

Determination of fatty acids and lipid classes in salmon oil by near infrared spectroscopy

International audience; Near-infrared (NIR) spectroscopy was evaluated as a rapid method for the determination of oleic, palmitic, linoleic and linolenic acids as well as omega-3, omega-6, and to predict polyunsaturated, monounsaturated and saturated fatty acids, together with triacylglycerides, diglycerides, free fatty acids and ergosterol in salmon oil. To do it, Partial Least Squares (PLS) regression models were applied to correlate NIR spectra with aforementioned fatty acids and lipid classes. Results obtained were validated in front of reference procedures based on high performance thin layer and gas chromatography. PLS-NIR has a good predictive capability with relative root mean squar…

Direct determination of minerals in human diets by infrared spectroscopy and X-ray fluorescence

The use of near and mid infrared spectroscopy and X-ray fluorescence (XRF) to determine the concentration of mineral elements in Spanish human diets was investigated. Thirty-five commercial baby foods, 6 children fast food menus and 13 university canteen menu samples were analysed by infrared and XRF spectroscopy and spectra evaluated by using reference data obtained by inductively coupled plasma optical emission spectroscopy (ICP-OES). Models for calcium, potassium, iron, magnesium, sodium and zinc determination were built and validated. Spectra were pre-treated by using different pre-processing algorithms (multiplicative scatter correction, standard normal variation, first derivate, ortho…

Electrochemical biosensing using hydrogel nanoparticles

Abstract Biology and medicine have seen great advancements in the development of nanobiosensors capable of characterizing and quantifying biomolecules. This review reports a systematic study of the usefulness of hydrogel nanoparticles (HNPs) in the different steps of the electroanalytical process developed in electrochemical biosensing systems. We illustrate the advantages offered by HNPs in detection of analytes with representative recent examples that highlight the scientific interest in widening the use of HNPs in electrochemical biosensing methods. We review different types of HNP-based electrochemical biosensors, such as enzyme, protein, and nucleic acids, in terms of their sensing per…

Direct determination of polymerised triacylglycerides in deep-frying vegetable oil by near infrared spectroscopy using Partial Least Squares regression

Abstract A green method for the determination of polymerised triacylglyceride (PTG) in deep-frying vegetable oils of different botanic origin has been developed employing near infrared (NIR) spectroscopy and Partial Least Squares (PLS) regression. Four different types of oil were heated during several hours, with and without the addition of foodstuff. NIR transmission spectra were obtained directly from sample aliquots stored in glass vials, thus avoiding the consumption of solvents and minimising waste generation. Variables employed for building the PLS models were selected applying interval PLS (iPLS) as well as Uninformative Variable Elimination-PLS (UVE-PLS). A global PLS model using sp…

Green Industrial Analysis

Development of biosensors for detection of alpha-fetoprotein: As a major biomarker for hepatocellular carcinoma

Abstract Alpha-fetoprotein as a multifunctional glycoprotein with a dual regulatory role in cancer and fetal activities is belonging to an albuminoid gene family. Due to important biological activities of alpha-fetoprotein in the adjustment of cancer, the level of this biomarker, majorly in liver carcinomas, abnormally is elevated. Also, the probability of high-risk or low-risk patients for chromosomal abnormalities can be identified by the serum level of alpha-fetoprotein. The detection of biomarkers possesses an important role in prognosis and early diagnosis of cancer and other diseases. So, the development of accurate and sensitive methods for measurement of alpha-fetoprotein is of grea…

Mineral analysis of human diets by spectrometry methods

Abstract Mineral element determination in human diets is very important for human health, due to the presence in foods of essential and toxic elements or their incorporation in the manipulation and cooking food process. Different instrumental techniques have been used to determine mineral elements in human diets, but atomic spectroscopy and mass spectrometry based ones are the most commonly employed. Sampling procedures for diet analysis are the main critically step for mineral element determination, being employed different standardised protocols. This review summarised critically the state-of-the-art of mineral analysis in human diets, considering sampling, sample preparation and determin…

Non-destructive analytical methods to study the conservation state of Apadana Hall of Persepolis.

Atmospheric and biological agents are the main enemies of the building material conservation. In this work an innovative methodological approach, based on Near Infrared Spectroscopy (NIR) and X-Ray Fluorescence Spectroscopy (XRF), has been employed to evaluate the conservation state of Persepolis limestone samples collected both, under a protective shelter and outside the shelter, at Apadana Audience Hall area in Persepolis. The use of NIR spectra permitted to discriminate, by using Principal Component Analysis (PCA), the differences between samples collected inside and outside the protective shelter and we have been able to identify a major degradation state of the out shelter stone sample…

Quality Control of Agrochemical Formulations by Diffuse Reflectance near Infrared Spectrometry

A near infrared (NIR)-based methodology has been developed for the determination of 11 pesticides in commercially available formulations. This solvent free, fast and environmentally friendly method was based on the direct measurement of the diffuse reflectance spectra of solid samples, a hierarchical cluster classification and the use of multivariate calibration models to determine each considered active principle in agrochemicals. The proposed partial least squares (PLS) models used for quantification of each compound were built from specific calibration sets composed of nine spectra corresponding to triplicate measurements of a single well characterised commercial sample and two addition…

Optimization of large-volume injection for the determination of polychlorinated biphenyls in children's fast-food menus by low-resolution mass spectrometry.

International audience; This study includes the determination of five indicator polychlorinated biphenyls (PCBs) (52, 101, 153, 138, and 180), six non-ortho PCBs (35, 80, 81, 77, 126, and 169), and two mono-ortho PCBs (28 and 118) in fast food for children. A freeze-dried sample of 10 g is extracted by using pressurized n-hexane in two 5 min cycles at 120 degrees C and 100 mbar. Fatty extracts were cleaned up by means of acetonitrile/n-hexane partitioning and gel-permeation chromatography. The fractionation of non-ortho, mono-ortho, and indicator PCBs was made on graphitized carbon solid-phase extraction cartridges by using n-hexane, n-hexane/toluene (99:1, v/v), and toluene as elution solv…

Determination at low ppm levels of dithiocarbamate residues in foodstuff by vapour phase-liquid phase microextraction-infrared spectroscopy

Abstract A methodology based on the vapour phase (VP) generation of carbon disulphide from non-volatile dithiocarbamate compounds has been developed for determination of pesticide residues in foodstuff at low ppm levels. The method involves a selective reaction combined with liquid phase microextraction (LPME) and transmission infrared measurements. The use of a home made transmission cell improved the detection limits (LOD) compared to the use of attenuated total reflectance measurements by a factor of approximately 80. Using the most appropriate experimental conditions for the CS2 generation and LPME preconcentration, the precision of the methodology, expressed as the relative standard de…

Determination of volatile organic compounds in contaminated air using semipermeable membrane devices

Abstract Semipermeable membrane devices (SPMDs) were evaluated as passive samplers for the determination of 26 volatile organic compounds (VOCs) in contaminated air of occupational environments. A direct methodology based on the use of head-space-gas chromatography–mass spectrometry (HS-GC–MS) was developed for VOCs determinations in SPMDs, without any sample pre-treatment and avoiding the use of solvents. A desorption temperature of 150 °C for 10 min was sufficient for a sensitive VOCs determination providing limits of detection in the range of 15 ng SPMD−1 for 21 of 26 studied compounds. Linear and equilibrium uptake models were established for each VOC from compound isotherms. Highly vol…

Recent advances in Nanomaterial-mediated Bio and immune sensors for detection of aflatoxin in food products

Abstract Aflatoxin is the most harmful mycotoxin which is ubiquitous in foods and agricultural supplies. Since the health of human population is largely determined by the condition of food-producing, contaminated foods and agricultural supplies with aflatoxin can put the safety of people in jeopardy and lead to some fatal disease. In 2003 estimated the annual cost of aflatoxin contamination in the U.S. at about $500 million strong concern for human life. There are a great demand for development of rapid, sensitive and specific methods for detection of aflatoxin at trace levels. The purpose of this review is limited to novel aflatoxin biosensors, paying special attention to those based on th…

Publishing in Green Analytical Chemistry

Determination of thallium in water samples

Abstract This article illustrates the developments of effective preconcentration techniques and highly sensitive detection methods for accurate measurements of Tl species at extremely low concentration in aqueous solutions. The literature on this topic was taken from the Analytical Abstracts in the period 1990–2005.

Sample Preparation Improvement in Polycyclic Aromatic Hydrocarbons Determination in Olive Oils by Gel Permeation Chromatography and Liquid Chromatography with Fluorescence Detection

Abstract The determination of 15 polycyclic aromatic hydrocarbons (PAHs) in olive oil samples has been improved in order to obtain a fast methodology with a low limit of detection through the combination of liquid–liquid extraction with acetonitrile and preparative gel permeation chromatography (GPC) prior to the injection of purified extracts into a C18 column. Acetonitrile–water was used as the mobile phase with a gradient from 50 to 95%, w/w, acetonitrile in 30 min. The oven temperature was maintained at 15°C, and fluorometric detection was made at a fixed excitation wavelength of 264 nm and variable, optimal emission wavelength for each analyte ranging from 352 nm for 11-H-benzo(b)fluor…

Determination of organic and inorganic mercury species in water and sediment samples by HPLC on-line coupled with ICP-MS.

This paper describes a preconcentration method for Hg(2+) and MeHg(+) in water samples using sodium diethyldithiocarbamate immobilized in polyurethane foam (PU-NaDDC) and an extraction method for several mercury species in sediment samples, including MeHg(+), EtHg(+) and PhHg(+), which is simple, rapid, and uses a single organic solvent. Separation and measurement were done by high-performance liquid chromatography on-line with inductively coupled plasma mass spectrometry (HPLC/ICP-MS). Initially, the test of recovery was applied using procedures compatible with HPLC. Under the optimum extraction conditions, recoveries of 96.7, 96.3 and 97.3% were obtained for MeHg(+), EtHg(+), and PhHg(+),…

Aptamer-based assay of biomolecules: Recent advances in electro-analytical approach

Electrochemical aptasensors, which are based on the specificity of aptamer-target recognition, with electrochemical transduction for analytical purposes have received particular attention due to their high sensitivity and selectivity, simple instrumentation, as well as low production cost. This review summarizes advances from 2009 to January 2017 in the development of electrochemical aptasensors for biological molecules, including small molecules, nucleic acids, and proteins. Various aptasensing strategies are assessed according to their potential for reaching relevant limits of sensitivity, specificity, and degrees of multiplexing. Furthermore, we address the remaining challenges and oppor…

Food Chemistry: Food quality and new analytical approaches

Peer Reviewed

Quality control Fourier transform infrared determination of diazepam in pharmaceuticals

A quality control procedure has been developed for the determination of diazepam in pharmaceuticals using Fourier transform infrared (FTIR) spectroscopy. The method involves the off-line extraction of diazepam with chloroform by sonication and direct determination in the extracts through peak area measurement in the interval between 1672 and 1682 cm(-1) using a baseline correction defined between 1850 and 1524 cm(-1). For standardization it was used an external calibration line established from standard solutions of diazepam in chloroform. The method provides a limit of detection of 0.04 mg per tablet (n=5), a relative standard deviation (R.S.D.) of 0.5% for 5 independent measurements of a …

Atomic fluorescence determination of inorganic arsenic in soils after microwave-assisted distillation

Abstract An inexpensive microwave-assisted distillation procedure has been developed for quantitative determination of inorganic arsenic in soils by atomic fluorescence spectrometry (AFS). After reduction of As(V) to its trivalent state with potassium iodide, inorganic arsenic was distilled as AsCl 3 that was finally determined by atomic fluorescence after hydride generation with NaBH 4 in HCl medium. The different parameters that control the distillation: concentration and volume of HCl, time of distillation, sample weight, and oven load, were studied. The methodology developed has a detection limit of 0.015 μg l −1 , which corresponds to a concentration of 0.006 μg of As per gram of soil,…

Mesoporous silica materials for use in electrochemical immunosensing

Abstract Silica-based electrochemical immunosensors recently gained much importance for detecting antigens and biomarkers responsible for cancer diagnosis. This review describes fabrication and chemical modification of the surfaces of mesoporous silica materials for biomedical and immunosensing applications. We also present a comprehensive overview of current developments and key issues in the determination of some biological molecules with particular emphasis on evaluating the models.

An environmentally friendly multicommutated alternative to the reference method for anionic surfactant determination in water

Abstract It has been developed a fully mechanized procedure for the spectrophotometric determination of anionic surfactants in water expressed in terms of SDS concentration. The reference method, based on the reaction of SDS with methylene blue (MB) followed by extraction in chloroform, was mechanized in order to reduce the consumption of organic solvents. The system was based on the multicommutation approach and provided a 35 times reduction of the waste production without sacrificing the figures of merit of the method in terms of sensitivity and repeatability, for a dynamic linear range from 0.2 to 1.7 mg l−1. Results obtained for washing water samples were comparable with those obtained …

Green Analytical Chemistry

Multi-pumping mechanised determination of selenium in natural waters by light emitting diode (LED) spectrometry

It has been developed a fully mechanised procedure for the determination of selenium in waters employing a LED based spectrometer and solenoid multi-pumps as solution propelling devices. The proposed method is based on the reaction of selenium with potassium iodide in an acidic medium to liberate iodine, which oxidizes Variamine Blue to form a violet-colour species which absorb at 530 nm. The system was mechanised using the multicommutation process and a stopped flow strategy in the final step reaction. The analytical curve was linear between 0.010 and 0.500 mg L-1, with an equation ΔA = 0.501 (± 0.004) C and r = 0.999. The limit of detection (3σ/S) obtained for the proposed method was 0.00…

Recent advances on portable sensing and biosensing assays applied for detection of main chemical and biological pollutant agents in water samples: A critical review

Abstract The quality analysis of water, pharmaceutical and environmental compounds is a basic subject for human health. The presence of low-quality drugs, biological toxins and chemical compounds in water or forbidden additives in the nourishments lead to irreversible problems in human health. Hence, multiple analytical approaches have been presented for investigating the quality of environmental, pharmaceutical, and food compounds and monitoring the detection of toxic compounds and pollutants in water. Sensing tools based on analytical strategies are required for identifying and quantifying the different pollutants including biological and chemical contaminants in water samples. Among diff…

Partial least squares attenuated total reflectance IR spectroscopy versus chromatography: the greener method

Method election is a complex task that must be done carefully in order to ensure the capability of analytical methodologies to provide appropriate data for problem solving. This is a real challenge in all fields, but especially with bioanalysis, which in many cases involves the need to do a large number of determinations in complex

Selective determination of clenbuterol residues in urine by molecular imprinted polymer—Ion mobility spectrometry

Abstract Clenbuterol is banned for sports use and strictly regulated in livestock industry. In this study, a procedure for the determination of clenbuterol residues in water and urine has been developed using selective supports combined with ion mobility spectrometry (IMS) determination. A molecular imprinted polymer (MIP) was used for efficient clean-up and preconcentration of clenbuterol followed to a dispersive liquid-liquid microextraction (DLLME) in order to improve selectivity and sensitivity of IMS determinations. Quantitative recoveries from 81 to 99% were obtained for water and spiked urine samples using MIP-DLLME-IMS method. A precision of 4.5%, established as the relative standar…

Environmental applications (air)

Abstract The use of solid sorbent-based devices for the monitoring of contaminants in the air is a widespread trend due to its versatility, physicochemical stability, and high enrichment factor. Active and passive sampling strategies have been developed for air monitoring using different materials, such as carbon-based organic polymers and inorganic sorbents. It has been updated in the literature regarding the most recent applications of the use of solid sorbent-based samplers for the monitoring of air in different sites such as rural, urban, industrialized, and indoor areas, including workplace environments for the evaluation of occupational exposure risks.

Development of a simple and low cost device for vapour phase Fourier Transform Infrared spectrometry determination of ethanol in mouthwashes

Abstract A new vapour phase manifold coupled with Fourier Transform Infrared (FTIR) spectroscopy was developed for ethanol determination in mouthwashes. Two microliters of samples were injected, without any previous pre-treatment into a reactor heated at 70 °C, and the vapour phase generated transported to the FTIR spectrometer using a carrier nitrogen flow of 6 ml min−1. FTIR spectra were continuously recorded, as a function of time, by accumulating two scans and employing 8 cm−1 nominal resolution. Analytical measurements for ethanol were made in the range from 1130 to 992 cm−1 with a baseline defined between 1158 and 957 cm−1. After ethanol measurement the carrier flow was increased to 3…

Nanomaterials and phase sensitive based signal enhancment in surface plasmon resonance

Measurement of small molecules in extremely dilute concentrations of analyte play an important role in different issues ranging from food industry to biological, pharmaceutical and therapeutical applications. Surface plasmon resonance (SPR) sensors can be a suitable choice for detection of small molecules based on interactions with biomolecules. However, sensitivity of the system for detection of these molecules is very low. Improving sensitivity has been a challenge for years. Therefore, different methods have been used to enhance SPR signals. The SPR signal enhancement using numerous nanomaterials has provided exciting results. Among various nanomaterials, metal nanoparticles (for instanc…

Towards minimization of chlorinated solvents consume in Fourier transform infrared spectroscopy determination of Propamocarb in pesticide formulations.

Abstract A method has been developed for Fourier transform infrared (FTIR) spectroscopy determination of Propamocarb in emulsifiable pesticide concentrate formulations. Five microliter sample was directly injected without any pretreatment in a CHCl 3 stream at 2 mL min −1 into a closed system and the FTIR spectra of sample and standard solutions were obtained using a nominal resolution of 4 cm −1 from 4000 to 900 cm −1 spectral region and accumulating 2 scans per spectrum. Propamocarb determination was based on the measurement of flow injection analysis (FIA) recording height established from FTIR peak area measurements from 1713 to 1703 cm −1 corrected using a baseline defined at 2000 cm −…

Nanotechnology, and scaffold implantation for the effective repair of injured organs: An overview on hard tissue engineering

The tissue engineering of hard organs and tissues containing cartilage, teeth, and bones is a widely used and rapidly progressing field. One of the main features of hard organs and tissues is the mineralization of their extracellular matrices (ECM) to enable them to withstand pressure and weight. Recently, a variety of printing strategies have been developed to facilitate hard organ and tissue regeneration. Fundamentals in three-dimensional (3D) printing techniques are rapid prototyping, additive manufacturing, and layered built-up and solid-free construction. This strategy promises to replicate the multifaceted architecture of natural tissues. Nowadays, 3D bioprinting techniques have prove…

Assessment of air passive sampling uptakes for volatile organic compounds using VERAM devices

Abstract A calibration chamber has been designed and employed for the simple and easy determination of uptake sampling rate (RS) of volatile organic compounds (VOCs) from air using passive samplers. A flow of clean air was continuously spiked, at a constant VOC concentration, by the microinjection of a standard solution by means of a T-type tube. The developed system allowed the complete evaporation at room temperature of the standard solution in acetone and the air concentration of VOCs was easily controlled by the regulation of the clean air flow, the standard solution concentration and its flow. Active sampling was employed for monitoring the true concentration of the evaluated compounds…

Determination of sugars in depilatory formulations: a green analytical method employing infrared detection and partial least squares regression.

A green analytical method was developed for the analysis of sugar-based depilatories. Three independent partial least squares (PLS) regression models were built for the direct determination of glucose, fructose and maltose without any sample pretreatment based on their attenuated total reflectance - Fourier transform infrared (ATR-FTIR) spectra. The models showed adequate prediction capabilities with root-mean-square-errors of prediction ranging from 7.04 to 12.55 mg sugar g(-1) sample. As a reference procedure, gradient liquid chromatography with on-line infrared detection, employing background correction based on cubic smoothing splines, was used. The analysis revealed changes in the suga…

Clean method for the simultaneous determination of propyphenazone and caffeine in pharmaceuticals by flow injection Fourier transform infrared spectrometry.

A procedure is proposed for the simultaneous FTIR determination of propyphenazone (PFZ) and caffeine (CAF) in pharmaceuticals. The method involves the dissolution of the active principles in CHCl 3 , followed by filtration of sample solutions to remove the excipients. PFZ is then determined by absorbance measurements at 1595 cm - 1 , using a baseline established between 2000 and 890 cm - 1 , and CAF by using the first-derivative values at 1712 cm - 1 , using solutions of PFZ and CAF for external calibration. The method was applied in both the stopped-flow and flow-injection modes, providing precise and accurate results for the analysis of real samples. The incorporation of a distillation un…

Characterization of petroleum-based products by infrared spectroscopy and chemometrics

Abstract The role of fossil fuels in providing the energy required for automobiles, factories and daily life has seriously concerned the authorities. Consistency of the quality of petroleum-based products is an important aspect of social and environmental criteria in a developed society. High-quality petroleum-based fuels would have several benefits (e.g., reduction in rate of consumption, less environmental pollution and durability of hardware). We review recent advances in the application of infrared spectroscopy in the petroleum industry. We focus on the methods proposed for the determination of a wide range of characteristics in petroleum-based products. We discuss methods based on the …

Recent advances of electrochemical and optical biosensors for detection of C-reactive protein as a major inflammatory biomarker

Abstract Early detection of inflammatory mediators including C-reactive protein (CRP) is of great diagnostic importance in many human diseases. CRP elevates very fast in conditions such as tissue injuries, infections, cancers, and renal and cardiovascular diseases. Conventional techniques for detecting CRP are based on antigen–antibody, agglutination, and precipitation reactions. Newer methods based on immunoturbidimetry and immunonephelometry are also time-consuming and relatively expensive. For solving these problems, highly efficient techniques based on CRP-biosensors have been introduced. Here, our aim was to summarize the features of recent biosensors for detection of CRP in biological…

Current advancement in immunosensing of p53 tumor suppressor protein based on nanomaterials: Analytical approach

Abstract The utility of detection of p53 in tomorrow's personalized health care field will mean early and accurate diagnosis of many types of cancers. This review is meant to provide an overview of the various types of immunosensors and immunoassay have been developed for determination of p53, along with significant advances over the last several years in related technologies. In addition, this review described: • Most frequently applied principles in immunoassay/immunosensing of p53. • The aspects of fabrication in the perspective of immunoassay/immunosensing applications. • The potential of various electrochemical, electrochemiluminescence immunosensors for the determination of p53 within…

Determination of arsenic and antimony in milk by hydride generation atomic fluorescence spectrometry

Abstract A highly sensitive procedure has been developed for total arsenic and antimony determination in milk samples by hydride generation atomic fluorescence spectrometry after microwave-assisted sample digestion. The discrete introduction of 2 ml of digested sample in the automated continuous flow hydride generation system allows us to reduce drastically the sample and HCl consume and to determine several elements from a same sample digestion. The method provides detection limits of 0.006 and 0.003 ng ml−1, a sensitivity of 2390 and 2840 fluorescence units per ng ml−1 for As and Sb respectively, and average relative standard deviation of 2.3% for As and 4.8% for Sb. The analysis of cow m…

Analysis of Sagunto Ibero-Roman votive bronze statuettes by portable X-ray fluorescence

Abstract The main objective of this work was the study of chemical composition of an important collection of Ibero-Roman votive bronze statuettes exposed in the Archaeological Museum of Sagunto (Spain). Precision and accuracy of the measurements were obtained developing a proper analytical method, also avoiding any possible damage to the studied objects using a portable energy dispersive X- ray fluorescence system. Principal Components Analysis (PCA) to discriminate between groups based on ratios Fe/Cu, Pb/Cu, Sn/Cu, Ag/Cu, Ni/Cu and Impurities/Cu were employed to observe differences between the used smelting, manufacturing processes and raw materials. The characterisation of bronze statuet…

Size Reduction of CdSe/ZnS Core−Shell Quantum Dots Photosensitized by Benzophenone: Where Does the Cd(0) Go?

The size of core-shell CdSe/ZnS quantum dots can be decreased by using the combined action of an n,π* aromatic ketone and UVA light. Energy-dispersive X-ray spectroscopy as well as X-ray photoelectron spectroscopy techniques gave information on the photosensitization mechanism and the eventual destiny of Cd(2+) and Se(2-) core ions. Our data support the electron transfer from the BP ketyl radical to Cd(2+), leading to Cd(0) and H(+), as well as to the recovery of benzophenone. Elemental Cd remains on the core and, eventually, can be oxidized to CdO. In addition, Se(2-) counterions disperse inside the solution mainly attached to protonated amine ligands. The Se(2-) combines with H(+), leadin…

RETRACTED: Optical bio(sensing) using nitrogen doped graphene quantum dots: Recent advances and future challenges

Abstract The exceptional optical properties and the presence of high number of reactive sites make nitrogen doped graphene quantum dots (N-GQDs) powerful tools in analytical nanoscience and nanotechnology. At the same time, their opto-electronics properties make them excellent nanomaterials for biomedical analysis aspects. This review aims to explore progress to date various features of N-GQDs for optical bio (sensing) of target analytes. Moreover, as another aim of this review is to provide insight into the intensity based spectroscopic methods which are applied in bio (sensing) discussing their advantages and disadvantages. More importantly, we discuss in detail different aspects of the a…

Synthesis and optimization of microwave-assisted exfoliated functionalized graphene as an efficient catalyst in biodiesel production

In this study, the capability of functionalized graphene was investigated as heterogeneous catalyst in biodiesel production from vegetable oil. Graphene oxide was fabricated from graphite via carrier improved method, and its exfoliation was carried out by microwave radiation. The exfoliated sample was reduced and sulfonated, being analyzed by Fourier transform Infrared, Scanning Microscopy Transmission Electron Microscopy, X-ray diffraction and element mapping. The catalyst was employed in biodiesel production reaction and effective reaction parameters were studied. The optimized reaction temperature, time and catalyst percentage were 178 °C, 3 h and 1.9% respectively. It was observed that …

Analytical potential of mid-infrared detection in capillary electrophoresis and liquid chromatography: a review.

Literature published in the last decade concerning the use of mid-infrared spectrometry as a detection system in separation techniques employing a liquid mobile phase is reviewed. In addition to the continued use of isocratic liquid chromatographic (LC) techniques, advances in chemometric data evaluation techniques now allow the use of gradient techniques on a routine basis, thus significantly broadening the range of possible applications of LC-IR. The general trend towards miniaturized separation systems was also followed for mid-IR detection where two key developments are of special importance. Firstly, concerning on-line detection the advent of micro-fabricated flow-cells with inner volu…

Novel approach for the determination of azithromycin in pharmaceutical formulations by Fourier transform infrared spectroscopy in film-through transmission mode

Abstract This work reports the development of a new method for the determination of azithromycin in pharmaceutical formulations employing Fourier transform infrared (FTIR) technique. The measurements were performed using a novel approach based on a film-through transmission mode. Several variables that could influence the analytical performance of the method were evaluated (solvent, nominal resolution, number of scans, mode of measurement and spectral region selected for measurement). Acetonitrile was the best solvent for the determination of azithromycin, employing the absorption band of the C O group at 1729 cm− 1. The extraction of azithromycin from the formulations was made by mechanica…

Green analytical chemistry

Simultaneous determination of Folpet and Metalaxyl in pesticide formulations by flow injection Fourier transform infrared spectrometry

Fourier transform infrared (FTIR) spectrometric methodology has been developed for the simultaneous determination of Folpet and Metalaxyl in pesticide formulations. The method involves the extraction of both active principles by sonication of the sample with CHCl3 and direct measurement of the absorbance using peak height values at 1798 cm −1 corrected with a baseline defined at 1810 cm −1 for Folpet, and peak area data established from 1677 to 1667 cm −1 corrected using a baseline from 1692 to 1628 cm −1 for Metalaxyl. Limits of detection (3 s) values of 17 and 16 gg −1 were found for Folpet and Metalaxyl, respectively, with results comparable with those found by liquid chromatography with…

Direct vapor generation Fourier transform infrared spectrometric determination of ethanol in blood

Abstract A new procedure is proposed for a direct determination of ethanol in plasma and whole blood. The method is based on the injection of a discrete sample volume of 10 μl into an electrically heated Pyrex glass reactor in which, at a temperature of 90 °C, the ethanol is volatilized and introduced by means of a N 2 carrier flow inside a long-path infrared gas cell and the corresponding flow analysis recording registered as a function of time. The measurement of the area of the flow injection recording, obtained from the absorbance of the transient signal in the range 1150−950 cm −1 , allows the direct quantification of ethanol upto 2 g l −1 , with a limit of detection of 0.020 g l −1 an…

Kinetic and thermodynamic insights into interaction of erlotinib with epidermal growth factor receptor: Surface plasmon resonance and molecular docking approaches.

Abstract Epidermal growth factor receptor (EGFR) plays an important role in cell proliferation at non-small cell lung cancer (NSCLC). Therefore, targeted therapy of cancer via this kind of receptor is highly interested. Small molecule drugs such as erlotinib and gefitinib inhibit EGFR tyrosine kinase and thus suppress cell proliferation. At this paper, erlotinib interaction with EGFR on the cell surface was studied via surface plasmon resonance (SPR) and molecular docking methods. Kinetic parameters indicated that erlotinib affinity toward EGFR was increased through increment of temperature. The thermodynamic analysis showed that van der Waals and hydrogen binding forces play a major role i…

Characterization of estuarine sediments by near infrared diffuse reflectance spectroscopy

It has been developed a partial least squares near infrared (PLS-NIR) method for the determination of estuarine sediment physicochemical parameters. The method was based on the chemometric treatment of first order derivative reflectance spectra obtained from samples previously lyophilized and sieved through a lower than 63 μm grid. Spectra were scanned from 833 to 2976 nm, averaging 36 scans per spectrum at a resolution of 8 cm-1, using chromatographic glass vials of 9.5 mm internal diameter as measurement cells. Models were built using reference data of 31 samples selected through the use of a hierarchical cluster analysis of NIR spectra of sediments obtained from the Ria de Arousa estuary…

Derivative Fourier transform infrared spectrometric determination of ethanol in alcoholic beverages

Abstract A derivative Fourier transform infrared (FT-TR) spectrometric procedure was developed for the direct determination of ethanol in alcoholic beverages, from beers to spirit samples. The method is based on first-order derivative FT-IR measurements between the peak at 1052 cm −1 and the valley at 1040 cm −1 , which are present in aqueous solutions and alcoholic beverages, by using a micro flow transmittance cell with ZnSe windows and a spacer of 0.029 mm. The method involves the accumulation of ten scans and provides accurate results in the determination of ethanol in alcoholic beverages without requiring any previous chemical treatment of the sample or a previous separation or extract…

Multicommutation cold vapour atomic fluorescence determination of Hg in water.

Abstract A multicommutation-based method has been developed for the on-line direct atomic fluorescence spectrometric (AFS) determination of Hg in waters without any previous sample treatment. The performance of the proposed procedure has been compared with that of a conventional AFS system based on continuous mode measurements. In short, the use of multicommutation, together with a reduction of the size of the liquid–gas phase separator, provides an increase of the laboratory productivity by improving the sample throughput by a factor of 3.6 and strongly reduces the sample consumed by a factor of 6 and reagent consumed by a factor of 8.4. The waste generation is reduced by a factor of 2.4 a…

Flow Injection Analysis– F ourier Transform Infrared Spectrometry ( FIA / FT ‐ IR )

The sections in this article are Advantages and Historical Perspective of the Use of FIA in FT-IR Direct Analysis of Samples by FIA/FT-IR FIA/FT-IR Determinations after Liquid Extraction FIA/FT-IR Determinations after Solid-Phase Extraction Enzymatic Analysis by FIA/FT-IR Vapor Generation FT-IR New Developments

Determination of lidocaine in urine at low ppm levels using dispersive microextraction and attenuated total reflectance–Fourier transform infrared measurements of dry films

Abstract IR spectra provide valuable information about biological systems and can be obtained with compactable and affordable instruments, but the lack of sensitivity of this technique hampers its use in the determination of drugs in clinical fluids. Taking lidocaine as a target molecule, in this paper we introduced a methodology for determining drugs in urine samples using infrared spectroscopy. The lack of sensitivity of the IR was compensated with the combination of an effective and straightforward dispersive liquid–liquid microextraction and the measurement of the dry film of the organic extracts through attenuated total reflectance (ATR). The method developed improves the sensitivity b…

Current air quality analytics and monitoring: a review.

This review summarizes the different tools and concepts that are commonly applied in air quality monitoring. The monitoring of atmosphere is extremely important as the air quality is an important problem for large communities. Main requirements for analytical devices used for monitoring include a long period of autonomic operation and portability. These instruments, however, are often characterized by poor analytical performance. Monitoring networks are the most common tools used for monitoring, so large-scale monitoring programmes are summarized here. Biomonitoring, as a cheap and convenient alternative to traditional sample collection, is becoming more and more popular, although its main …

Nanomaterial-based electrochemical immunosensors as advanced diagnostic tools

A literature survey has been made of recent advances in the use of new nanomaterials for the biosensing of different biomolecules, which have opened new horizons in identifying and quantifying biomolecules, for possible early diagnosis of disease. Nanomaterials show similar dimensions to biomolecules like proteins (enzymes, antigens and antibodies) and DNA. The integration of nanomaterials with biomaterials results in novel hybrid nanobiomaterials with synergetic properties and functions. In this review, we will discuss recent progress in the field, describing the basic concepts of nanomaterial-based platforms for development and expansion of immunosensors and nanosensors. We present an ove…

Recent advances on nanomaterial based electrochemical and optical aptasensors for detection of cancer biomarkers

Abstract Cancer is a real menace to all societies globally since it is the leading cause of premature mortality in men and women. The incidence of malignancies is enhancing as a result of plenty factors. Physically and economically concerns that occur in cancers patients cannot be neglected. However, current diagnostic methods and cure duration do not fulfill patients requirements. Therefore, it is essential to detect and diagnose cancer biomarkers as soon as possible and overcome the current burdens. Novel aptasensors is emerging as one of the most promising strategies for early recognition of cancer. Aptamers an artificial DNA or RNA sequences, possess plenty of merits such as easy produc…

Univariate near infrared methods for determination of pesticides in agrochemicals

Abstract It has been developed a general strategy for the determination of pesticides in agrochemicals by Fourier transform near infrared (FT-NIR) spectroscopy. The methodology is based on previous extraction of the active principles through sonication with acetonitrile and direct determination by transmission measurements, using glass vials as measurement cells and univariate calibration at selected wavenumbers as a function of the pesticide to be analyzed. Chlorsulfuron, metamitron, iprodione, pirimicarb, procymidone and tricyclazole were used as test molecules and data obtained by FT-NIR for 20 samples containing one of these active principles compare well with those found by reference l…

Optical and electrochemical DNA nanobiosensors

In the past two decades, nanoscale advanced materials have been explored for biosensing molecules, so new horizons have opened up for identifying and quantifying biomolecules, and possible early diagnosis of diseases. DNA nanobiosensors show promise. This article provides an overview on their optical and electrochemical aspects. We discuss recent progress in this field, describing basic concepts of molecular beacons and quantum dots as optical nano-imaging systems. Also, carbon nanotubes provide a platform for development and advancement of electrochemical DNA nanobiosensors, which are increasingly being implemented as robust tools for detection in biomedical sciences. Refereed/Peer-reviewed

Scientometric Picture of the Evolution of the Literature of Automation in Spectroscopy and Its Current State

Abstract The current study focuses on the status of automation and mechanization in spectroscopy for analytical chemistry publications compiled during the period 1980–2006, in Analytical Abstracts. Flow injection analysis (FIA), sequential injection analysis (SIA), multicommutation, and monosegmented and segmented flow strategies were considered. For assessing the evolution of scientific productivity, the total number of publications concerned with the different methodologies was evaluated. In order to provide a picture of the state of the art of this field, the most important journals, the most active authors, and the most productive countries in the field of automation were evaluated in t…

A Review on Molybdenum Determination in Solid Geological Samples

This review highlights the necessity for the development of proper sampling and storage, fast pretreatment methodology followed by highly sensitive detection for the determination of molybdenum in geological samples. Distribution of concentration and chemical speciation of molybdenum analysis in solid geological matrices have also been discussed.

Green Solvents for Analytical Separation and Analyses

The alternatives to the use of organic solvents that have been offered by the scientific literature reviewed. In order to look at the best solvents from both analytical and sustainable view points, the use of water under superheated conditions, supercritical fluids, renewable organics, ionic liquids, and aqueous solutions of amphiphillic compounds, have been evaluated. As a general conclusion, it can be seen that, at present, green alternatives to the traditional organic solvents employed in analytical separations and analysis that are being well explored are the capabilities of the use of alcohols, supercritical fluids, and superheated water; and remain unexplored tremendous possibilities …

Nano-delivery system targeting to cancer stem cell cluster of differentiation biomarkers

Cancer stem cells (CSCs) are one of the most important origins of cancer progression and metastasis. CSCs have unique self-renewal properties and diverse cell membrane receptors that induced the resistance to the conventional chemotherapeutic agents. Therefore, the therapeutic removal of CSCs could result in the cancer cure with lack of recurrence and metastasis. In this regard, targeting CSCs in accordance to their specific biomarkers is a talented attitude in cancer therapy. Various CSCs surface biomarkers have been described, which some of them exhibited similarities on different cancer cell types, while the others are cancer specific and have just been reported on one or a few types of …

Partial least squares-near infrared determination of pesticides in commercial formulations

Abstract A solvent free, fast and environmentally friendly near infrared-based methodology (NIR) was developed for pesticide determination in commercially available formulations. This methodology was based on the direct measurement of the diffuse reflectance spectra of solid samples and a multivariate calibration model (partial least squares, PLS) to determine the active principle concentration in commercial formulations. The PLS calibration set was built on using the spiked samples by mixing different amounts of pesticide standards and powdered samples. Buprofezin, Diuron and Daminozide were used as test analytes. Concentration of Buprofezin in the samples was calculated employing a 4-fact…

Hard Cap Espresso Machine Extraction of Polyphenolic Compounds from Pulses

A hard cap espresso machine was employed for the extraction of polyphenolic compounds from food samples as dry legumes and pulses. 100 mg of ground dry sample was mixed with a dispersing agent and placed in a refillable stainless steel capsule with a borosilicate filter. A complete polyphenol extraction was achieved by using 150 mL ethanol 50 % (v/v) in water and determined by Folin-Ciocalteu spectrophotometric method. The method provided a limit of detection of 0.4 mg g<sup>-1</sup>. The whole extraction procedure was achieved in less than one minute using the mild extraction conditions of 72°C and 19 bars given by the domestic machine. Fifteen varieties of food samples (3 lent…

Attenuated Total Reflection-Fourier transform infrared analysis of the fermentation process of pineapple

Abstract A direct and reagent free procedure has been developed to monitor the fermentation process of pine apple nectar using Attenuated Total Reflectance Fourier-transform mid-infrared spectrometry (FT-IR) and multivariate analysis. A classical 4 2 design for standards was employed for calibration using the information in the spectral range from 907 to 1531 cm −1 of the first order derivative spectra after mean centering of infrared data. The root mean square error of calibration (RMSEC) of 0.040, 0.021, 0.063 and 0.074% w/w were obtained for glucose, fructose, saccharose and ethanol, respectively, and a mean relative validation error of 2.9, 2.1, 2.6 and 3.6% was achieved for glucose, fr…

Recent advances on application of peptide nucleic acids as a bioreceptor in biosensors development

Abstract The analogs of DNA are unique biomedical tools that are broadly utilized to develop different types of biosensors. Peptide nucleic acids (PNA) are an individual and notable class of nucleic acid analogs due to their unique, novel physicochemical and biochemical characteristics, stability and resistance to nuclease and protease enzymes, significant interactions with complementary strands and remarkable hybridization attributes. Therefore, they are employed in the preparation and fabrication of various types of functional biosensors. In other words, immobilization of PNA as an appropriate diagnostic probe on the surface of electrochemical and optical converters lead to the fabricatio…

Are deep eutectic solvents useful in chromatography? A short review.

A literature update has been done concerning Deep Eutectic Solvents (DES) use in chromatography applications. The literature survey was based on the period from 2010 till 2020 and manuscripts reported in the data bases Web of Science and Scopus. The use of DES as mobile phase and mobile phase additives, stationary phases and solid phase modifiers and the use of DES as reaction solvents for chromatography use, were evaluated. Emphasis was placed on the differentiation of DES and Ionic Liquids (ILs) and the advanced green characteristics of the new solvents as compared with traditional organic solvents and ILs with a look into the drawbacks and future perspectives in the field of separation m…

Background Correction and Multivariate Curve Resolution of Online Liquid Chromatography with Infrared Spectrometric Detection

J.K. acknowledges the “V Segles” grant provided by the University of Valencia to carry out this study. Authors acknowledge the financial support of Ministerio de Educación y Ciencia (Projects AGL2007-64567 and CTQ2008-05719/BQU) and Conselleria d'Educació de la Generalitat Valenciana (Project PROMETEO 2010-055).

Miniaturized solid-phase extraction techniques

More than 80% of analysis time is spent on sample collection and sample preparation, so sample preparation is a critical part of the analytical process. Traditionally, liquid-liquid extraction was developed and employed to screen for general unknowns. However, solid-phase extraction (SPE) is becoming highly popular as an alternative, due to its simplicity and economy in terms of time and solvent. This review summarizes the current state of the art and the future prospects for green analytical chemistry with special emphasis on environment-friendly sample-preparation techniques based on the solid phase. We discuss in detail miniaturized SPE techniques, based on the most relevant, most repres…

Speciation of methylmercury in market seafood by thermal degradation, amalgamation and atomic absorption spectroscopy

Sample thermal decomposition followed by mercury amalgamation and atomic absorption has been employed for the determination of methylmercury (MeHg) in fish. The method involves HBr leaching of MeHg, extraction into toluene, and back-extraction into an aqueous l-cysteine solution. Preliminary studies were focused on the extraction efficiency, losses, contaminations, and species interconversion prevention. The limit of detection was 0.018µgg(-1) (dry weight). The intraday precision for three replicate analysis at a concentration of 4.2µgg(-1) (dry weight) was 3.5 percent, similar to the interday precision according to analysis of variance (ANOVA). The accuracy was guaranteed by the use of for…

Electrochemical biosensing using N-GQDs: Recent advances in analytical approach

Abstract This review is meant to provide an overview of the electrochemical biosensors based on Nitrogen doped graphene quantum dots (N-GQDs) for analytical approaches, along with significant advances over the last several years in related technologies. In addition, this review described: i) Most frequently applied principles in biosensing based on of N-GQDs ii) The aspects of fabrication in the perspective of biosensing applications iii) The potential of various electrochemical, biosensors for the determination of target analytes within sub-micromolar range and the circumvention of the most serious problem in biosensing will be discussed. iv) Some of multiplex electrochemical biosensors ha…

Low temperature headspace desorption of volatile organic compounds trapped in air sampling solid-supports

Environmental context. The monitoring of volatile organic compounds (VOCs) in air is of great importance for air quality on both local and global scales. The determination of VOCs can be carried out by gas chromatography–mass spectrometry (GC-MS) after active or passive sampling and (high temperature) thermal desorption. An attractive alternative would be to combine GC-MS with headspace (HS) systems as it allows simpler, faster, low temperature desorption. We present here the first report of HS-GC-MS for the determination of VOCs in air sampled using solid supports. Abstract. The use of a headspace (HS) for low temperature desorption of VOCs, previously sorbed from indoor air on solid supp…

Modified locally weighted—Partial least squares regression improving clinical predictions from infrared spectra of human serum samples

Locally weighted partial least squares regression (LW-PLSR) has been applied to the determination of four clinical parameters in human serum samples (total protein, triglyceride, glucose and urea contents) by Fourier transform infrared (FTIR) spectroscopy. Classical LW-PLSR models were constructed using different spectral regions. For the selection of parameters by LW-PLSR modeling, a multi-parametric study was carried out employing the minimum root-mean square error of cross validation (RMSCV) as objective function. In order to overcome the effect of strong matrix interferences on the predictive accuracy of LW-PLSR models, this work focuses on sample selection. Accordingly, a novel strateg…

Near Infrared Spectroscopy Detection and Quantification of Herbal Medicines Adulterated with Sibutramine.

There is an increasing demand for herbal medicines in weight loss treatment. Some synthetic chemicals, such as sibutramine (SB), have been detected as adulterants in herbal formulations. In this study, two strategies using near infrared (NIR) spectroscopy have been developed to evaluate potential adulteration of herbal medicines with SB: a qualitative screening approach and a quantitative methodology based on multivariate calibration. Samples were composed by products commercialized as herbal medicines, as well as by laboratory adulterated samples. Spectra were obtained in the range of 14,000-4000 per cm. Using PLS-DA, a correct classification of 100% was achieved for the external validatio…

Modulating tumor hypoxia by nanomedicine for effective cancer therapy

Hypoxia, a characteristic feature of tumors, is indispensable to tumor angiogenesis, metastasis, and multi drug resistance. Hypoxic avascular regions, deeply embedded inside the tumors significantly hinder delivery of therapeutic agents. The low oxygen tension results in resistance to the current applied anti-cancer therapeutics including radiotherapy, chemotherapy, and photodynamic therapy, the efficacy of which is firmly tied to the level of tumor oxygen supply. However, emerging data indicate that nanocarriers/nanodrugs can offer substantial benefits to improve the efficacy of current therapeutics, through modulation of tumor hypoxia. This review aims to introduce the most recent advance…

An on-line system for preconcentration and determination of lead in wine samples by FAAS

A flow injection method has been developed for the direct determination of free available Pb(II) and total Pb content in wine samples. The method is based on the chemical sorption of Pb(II), from pH 7 buffered solutions, on a packed polyurethane foam column, modified by addition of 2-(2-benzothiazolylazo)-p-cresol (BTAC). After this step, lead was directly eluted with a stream of 0.1 mol l(-1) HCl into an air C(2)H(2) flame in which lead was determined by atomic absorption spectrometry. Total lead was analyzed after sample digestion with nitric acid and hydrogen peroxide, being free available lead determined by direct sample on-line preconcentration and elution. The method provides a limit …

A multinjection strategy for mercury speciation.

Abstract A multiinjection strategy has been developed to increase the sampling throughput of the high-performance liquid chromatography determination of inorganic-mercury, methylmercury, ethylmercury and phenylmercury. The method involves the injection of samples each 3.5 min, in spite of the fact that phenylmercury retention time corresponds to 9.04 min. In the selected conditions, the sampling frequency was 11 h −1 in front of that of 6 h −1 , obtained by conventional injection of each sample after the complete elution of Hg species. Additionally, the analytical reagents consumption was reduced drastically in almost 50%. The main characteristics of the chromatographic separation were main…

Liquid chromatography-Fourier transform infrared spectrometric determination of cholesterol in animal greases

Abstract Stearic acid, cholesterol and cholesteryl palmitate have been separated in less than 14 min by liquid chromatography on a column (3.9 mm i.d.×150 mm) of Nova-Pack C 18 (5 μm) using chloroform–acetonitrile (45 : 55) as mobile phase pumped at 0.5 ml min −1 ; Fourier transform infrared (FTIR) spectrometry was employed for both, general detection at 2868 or 2855 cm −1 and selective detection at 3285 cm −1 for stearic acid and 3526 cm −1 for cholesterol. In all cases a baseline established at 3900 cm −1 , 9-point smoothing and chromatographic peak height measurements were used. The method has been validated by application to the determination of cholesterol in animal greases and fish oi…

Room-temperature ionic liquid-based electrochemical nanobiosensors

Abstract Room-temperature ionic liquids (RTILs) have proved to be excellent materials for applications in electrochemistry. We review progress in constructing high-performance electrochemical biosensors. We also discuss: • different modified electrodes based on RTILs for biosensing applications; • different routes for enzyme biosensing based on RTIL-modified electrodes; • incorporation of biorecognition elements into RTIL-based electrodes; • electroanalytical applications of RTIL-based modified electrodes; and, • recent developments in which the advantages of ILs as a medium for biosensing were realized. We also summarize the latest developments in the applications of RTIL-based electrochem…

Non-chromatographic speciation of toxic arsenic in vegetables by hydride generation-atomic fluorescence spectrometry after ultrasound-assisted extraction.

A non-chromatographic, sensitive and simple analytical method has been developed for the determination of toxic arsenic species in vegetable samples by hydride generation-atomic fluorescence spectrometry (HG-AFS). As(III), As(V), dimethylarsinic acid (DMA) and monomethylarsonic acid (MMA) were determined by hydride generation-atomic fluorescence spectrometry using a series of proportional equations. The method is based on a single extraction of the arsenic species considered from vegetables through sonication at room temperature with H(3)PO(4) 1 mol L(-1) in the presence of 0.1% (w/v) Triton XT-114 and washing of the solid phase with 0.1% (w/v) EDTA, followed by direct measurement of the co…

Evaluation of working air quality by using semipermeable membrane devices

Abstract It has been evaluated the use of semipermeable membrane devices (SPMDs) as passive samplers of organophosphorus pesticides from air, in order to determine the contamination of working environments. Additionally, the use of SPMDs as portable samplers has been also considered. The analytical methodology for the determination of diazinon, chlorpyrifos-methyl, pirimiphos-methyl, chlorpyrifos and fenthion in SPMDs exposed to contaminated air was based on microwave-assisted extraction and gas chromatography with mass spectrometry determination. Limit of detection (LOD) values from 2 to 4 ng SPMD−1 and repeatability from 2 to 7% were obtained by using the aforementioned methodology. Theor…

An integrated approach of analytical chemistry

The tremendous development of physical methods of analysis offers an impressive number of tools to simultaneously determine a large number of elements and compounds at very low concentration levels. Todays Analytical Chemistry provides appropriate media to solve technical problems and to obtain correct information about chemical systems in order to take the most appropriate decisions for problem solving. In recent years the development of new strategies for sampling, sample treatment and data exploitation through the research on field sampling, microwaveassisted procedures and chemometrics, additionally the revolution of the analytical methodology provided by the development of flow analysi…

Multicommutation as an environmentally friendly analytical tool in the hydride generation atomic fluorescence determination of tellurium in milk.

The aim of this study is to show the advantages of the emerging multicommutation methodology based on the use of solenoid valves for Te determination in milk by hydride generation atomic fluorescence spectrometry (HG-AFS). The delivery of a series of alternating sequential insertions of small volumes of samples and reagents gives rise to new hydrodynamic processes and exciting analytical potentials by controlling the time of flow through the on/off-switched solenoid valves. This drastically reduces the reagent consumption by a factor of 4 and the generation of effluents (590 mL h(-1) instead of 750 mL h(-1) generated by the continuous-mode measurement) and also provides an improvement in th…

New background correction approach based on polynomial regressions for on-line liquid chromatography-Fourier transform infrared spectrometry.

Abstract In the present study a new approach for the chemometric background correction in on-line gradient LC–FTIR is introduced. For this purpose, the spectral changes of the elution mixture during gradient elution were analyzed applying 2D correlation spectroscopy. The fundamentals of the new background correction algorithm, based on polynomial fits calculated from a reference spectra matrix (Polyfit-RSM method) are explained. The Polyfit-RSM approach was applied on blank gradient runs as well as on LC–FTIR data obtained from the injection of a soft drink sample using acetonitrile:water as eluent. Results found were critically assessed and compared to those obtained by two previous backgr…

Univariate method for background correction in liquid chromatography–Fourier transform infrared spectrometry

An univariate method is proposed for background correction in on-line gradient liquid chromatography-Fourier transform infrared (LC-FTIR) spectrometry using acetonitrile:water as mobile phase components. The method is based on the calculation of the ratio of absorbances (AR) at two characteristic wavenumbers for each spectrum. This parameter is subsequently used to locate the most appropriated eluent spectrum within a reference spectra matrix (RSM) to be subtracted from each spectrum included in the sample chromatogram. To correct minor changes in eluent spectra intensity during the elution of analytes, a correction factor (Kf), defined as the ratio of the absorbance of the sample and the s…

Using semi-permeable membrane devices as passive samplers

Abstract We discuss the present state of, and future developments in, using semi-permeable membrane devices (SPMDs) for environmental monitoring of organic pollutants. SPMDs allow the determination of time-weighted average concentrations of bioavailable pollutants in the sampled media, reducing significantly the costs of analysis compared with active samplers. We summarize developments in SPMDs, including simplified devices and devices modified by incorporating solvents other than triolein, and applications. We review contaminants (e.g., organotin compounds, polycyclic musk, triclosan, petroleum biomarkers, nitrated PAHs, polychlorinated naphthalenes and a wide range of pesticides sampled i…

Quantitative Analysis, Infrared

In this article, after reviewing the different mathematical methods used in quantification we will describe and discuss their respective advantages and inconveniences. First of all, different examples of applications of infrared (IR) spectroscopy, used with or without other analytical chemistry methods, will be presented. Some examples of direct quantitative analysis in food analysis will be reviewed: lipids (measurement of unsaturation degrees, lipids determination), carbohydrates, proteins (secondary structures, quantitative analysis). We will also focus on original examples of the use of IR spectroscopy combined with enzymes. Secondly, some examples of Fourier transform infrared (FTIR) a…

Speciation analysis of food

Multipumping Nitrite Determination in Exhaled Breath Condensate

Abstract A flow system based on multicommutation is proposed for the rapid, clean, and inexpensive determination of nitrites in small volumes of breath condensates. The procedure exploits the colorimetric detection of nitrite with the Griess reagent [0.03% naphthylethylene diamine dihydrochloride (NED), 0.5% sulpfhanilamide, and 3.0% phosphoric acid] in acidic medium at 540 nm correcting the variations of the baseline with measurements at 424 nm. The flow system was designed with a set of solenoid micropumps to minimize sample and reagent consumption and waste generation. The detection limit was estimated as 3.8 ng mL−1 (99.7% confidence level) with a linear response ranging up to 500 ng mL…

Recent developments and future trends in solid phase microextraction techniques towards green analytical chemistry.

Solid phase microextraction find increasing applications in the sample preparation step before chromatographic determination of analytes in samples with a complex composition. These techniques allow for integrating several operations, such as sample collection, extraction, analyte enrichment above the detection limit of a given measuring instrument and the isolation of analytes from sample matrix. In this work the information about novel methodological and instrumental solutions in relation to different variants of solid phase extraction techniques, solid-phase microextraction (SPME), stir bar sorptive extraction (SBSE) and magnetic solid phase extraction (MSPE) is presented, including prac…

Hydride generation atomic fluorescence spectrometric determination of ultratraces of selenium and tellurium in cow milk

Abstract A sensitive procedure has been developed for selenium and tellurium determination in milk by hydride generation atomic fluorescence spectrometry (HG-AFS) after microwave-assisted sample digestion. The method provides sensitivity values of 1591 and 997 fluorescence units ng−1 ml−1 with detection limits of 0.005 and 0.015 ng ml−1 for Se and Te, respectively. The application of the developed methodology to the analysis of cow milk samples of the Spanish market evidenced the presence of concentration ranges from 11.1 to 26.0 ng ml−1 for Se, and from 1.04 to 9.7 ng ml−1 for Te having found a good comparability with data obtained after dry-ashing of samples.

Analysis of Caffeine, Sweeteners, and Other Additives in Beverages by Vibrational Spectroscopy

This chapter presents a review of the scientific literature on the use of vibrational spectroscopy, near-infrared (NIR), mid-infrared (mid-IR), and Raman, for the analysis of caffeine, sweeteners, and other additives in beverages and related products. Direct analysis procedures of coffee and tea, for both classification according to precedence or variety and quantitative determination of caffeine, are available. For beverage analysis, caffeine has been determined by direct attenuated total reflection (ATR) measurement or by transmission spectroscopy in the mid-IR region after extraction with chloroform. Different strategies have been employed for the analysis of sweeteners in beverages and …

Fourier transform infrared spectrometric determination of Ziram.

A procedure has been developed for vapour-phase Fourier transform infrared determination of Ziram, a dithiocarbamate pesticide. The method is based on the evolution of CS(2), after decomposition of the dithiocarbamate with diluted H(2)SO(4) at 50 degrees C. The CS(2) evolved was swept by a carrier flow of nitrogen to a laboratory-made infrared gas cell of 39 mm pathlength and 490 mul volume. The signals were registered as a function of time. The area of peaks obtained from absorbance measurement in the wavenumber range between 1600 and 1450 cm(-1) were interpolated in a calibration line established from Ziram standards treated in the same way as samples. The method provided an absolute limi…

Determination of quality parameters of beers by the use of attenuated total reflectance-Fourier transform infrared spectroscopy

Abstract The estimation of important quality parameters of beers, such as original and real extracts and alcohol content, has been evaluated by attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) using a partial least square (PLS) calibration approach. Two sample populations, one consisting of 24 samples and other of 21 samples, obtained from the Spanish market and covering different types of beer were used. The first set was used for building and validating the model, whereas the second, measured 6 months after, was used for evaluating its robustness. The spectral range and the size of the calibration set and its suitability for building the PLS model have been …

Magnetic molecularly imprinted polymers for the selective determination of cocaine by ion mobility spectrometry

Abstract Magnetic molecularly imprinted polymers (MMIPs) were prepared for cocaine recognition by bulk polymerization in the presence of magnetic nanoparticles (MNPs). Two reagents (polyethylene glycol (PEG) and 3-(trimethoxysilyl)propyl methacrylate (V)) were used for MNPs modification. MMIPs were characterized and compared in terms of loading capacity, reusability, accuracy and precision for the extraction of cocaine from saliva samples. It was observed that V-MMIPs gave higher physical stability than PEG-MMIPs. Thus, V-MMIP were used for the analysis of cocaine users saliva. The developed procedure based on ion mobility spectrometry (IMS) provided limits of detection and quantification o…

Dielectric spectroscopy as a potential technique for prediction of kiwifruit quality indices during storage

Dielectric spectroscopy has been employed as a simple, low cost and a non-destructive way for prediction of some physicochemical indices of kiwifruit during storage. A parallel-plate capacitor was developed and supplied with sinusoidal voltage waves within a frequency range of 40 kHz – 20 MHz. Dielectric properties of samples were measured by the dielectric sensor. Additionally, changes associated with fruit ripening properties, including firmness, total soluble solid (TSS) and pH were determined as a function of time at 2 °C. The results showed that storage time significantly affected the quality characteristics of kiwifruit. Artificial neural networks (ANNs) were employed to develop model…

Early detection of contamination and defect in foodstuffs by electronic nose: A review

Abstract Electronic nose (e-nose) has emerged as a potential instrument in various areas of food safety assessment for rapid early detection of contamination and defect in food production chain. E-nose is an innovative measurement system designed for detecting and discriminating complex odors through mimicking the working mechanism and the principal building blocks of the mammalian olfactory system. This paper describes a literature update of the applications of the e-nose for ensuring health and safety in the food industry. Finally, its future trend, perspectives and challenging problem are also mentioned.

Attenuated total reflectance infrared determination of sodium nitrilotriacetate in alkaline liquid detergents

Abstract An attenuated total reflectance infrared (ATR–FTIR) method has been developed for the direct determination of the chelating agent sodium nitrilotriacetate (NTA) in high pH cleaning formulations. Aqueous samples and standards were placed directly on the diamond ATR cell without any pre-treatment and FTIR spectra were recorded between 4000 and 600 cm−1. Measurement conditions were evaluated. Results obtained for five different commercial formulations containing from 6.22 to 9.25% (w/w) of NTA were in good agreement with the manufacturer's declared content (differences between 3.2 and −3.7%). Recovery studies evidenced the accuracy of the developed method, having found values between …

A spectrophotometric flow procedure for the determination of cationic surfactants in natural waters using a solenoid micro-pump for fluid propulsion

An automatic flow-analysis procedure for spectrophotometric determination of cationic surfactants in surface water using a solenoid micro-pump for propelling solutions of reagents and sample is des...

Detection and characterization of emerging psychoactive substances by ion mobility spectrometry

Rapid detection and identification of novel psychoactive substances (NPS) continues to present significant analytical challenges to forensic and analytical chemists. Ion mobility spectrometry (IMS) has been traditionally considered as the analytical technique of choice to detect illicit drugs in security points in airports, borderlines and customs. Databases of the reduced mobility (K0 ) values of illicit drugs are available in the scientific literature and they should be completed with data of emerging designer drugs. In this paper, we have evaluated the effect of different measurement conditions and determined the K0 values of an important number of NPS including different families; such …

Cubic smoothing splines background correction in on-line liquid chromatography–Fourier transform infrared spectrometry

A background correction method for the on-line coupling of gradient liquid chromatography and Fourier transform infrared spectrometry (LC-FTIR) is proposed. The developed approach applies univariate background correction to each variable (i.e. each wave number) individually. Spectra measured in the region before and after each peak cluster are used as knots to model the variation of the eluent absorption intensity with time using cubic smoothing splines (CSS) functions. The new approach has been successfully tested on simulated as well as on real data sets obtained from injections of standard mixtures of polyethylene glycols with four different molecular weights in methanol:water, 2-propano…

Gamificación: El concurso como actividad grupal de enseñanza/aprendizaje

[EN] The present study consist of the use of game mechanics to promote the development of applications and activities to stimulate, in an attractive way but without sacrificing the rigor required, the teaching and learning in the subjects of Chemistry and Analytical Chemistry in Chemistry degree.

Fourier transform infrared spectrometric determination of Malathion in pesticide formulations

Abstract An environmentally friendly methodology has been developed for quality control analysis of emulsifiable concentrate pesticide formulations containing Malathion as active ingredient, using flow injection analysis (FIA)–Fourier transform infrared (FTIR) spectrometry. Five microlitres samples were directly injected into a 3 ml closed FIA manifold, in which 2 ml of CHCl 3 was re-circulated at 1.96 ml min −1 . After homogenisation and sample measurement, 2 μl volumes of a Malathion standard were injected, taking absorbance measurements after each injection. Peak height of the chemigrams, established from peak area values between 1027 and 1017 cm −1 , corrected with a baseline fixed from…

Multicommutation-NIR determination of Hexythiazox in pesticide formulations.

A multicommutated flow-system was designed in order to increase analytical throughput and for controlling thermal effects on the NIR spectra for determination of Hexythiazox in pesticide formulations. An on-line standard addition was carried out showing the versatility and repeatability of multicommutation for the on-line mixing and dilution of solutions. Results obtained for commercial samples were statistically comparable with those obtained by an HPLC-reference method. Multicommutation-NIR allows the analysis of 52 samples per hour, in front of the 30 samples per hour analyzed by the NIR-batch procedure and the 7 samples per hour analyzed by HPLC-reference method.

A fast method for apatite selective leaching from granitic rocks followed through rare earth elements and phosphorus determination by inductively coupled plasma optical emission spectrometry

Abstract Rare earth elements (REE) and phosphorus (P) in apatite were determined using inductively coupled plasma optical emission spectrometry (ICP-OES) after partial dissolution of the granitic rocks and pure apatite. The dissolution was performed with nitric acid in an open system and the matrix elements were separated by a cation exchange procedure. Samples of pure apatite from granitic rocks were dissolved with, 0.14 mol L −1 nitric acid. The results showed that the release of REE is due to apatite leaching because it could be assessed by comparing the chondrite-normalised pattern corresponding to the rocks and the pure apatite. Similar results were found for absolute REE abundance fro…

Direct Analysis of Samples

Fourier transform infrared determination of Fluometuron in pesticide formulations

Abstract A single method has been developed for Fourier transform infrared (FTIR) determination of Fluometuron in pesticide formulations. Samples were ultrasonically shaken with CHCl3 for 5 min and the FTIR spectra of sample extracts and standards were obtained at a nominal resolution of 4 cm−1 from 4000 to 900 cm−1 accumulating 25 scans. Fluometuron determination is based on the measure of peak area from 1342 to 1321 cm−1 corrected using a baseline defined from 1352 to 1294 cm−1. This procedure provided a limit of detection of 6.5 μg g−1, a sensitivity of 0.852 a.u. g mg−1 for a pathlength of 0.11 mm, a relative standard deviation of 1.6% for three analysis of a sample containing 50.4% (w/…

Environmentally friendly analytical chemistry through automation: comparative study of strategies for carbaryl determination with p-aminophenol

Abstract A flow system, based on multicommutation and binary sampling, has been developed for improving the automated spectrophotometric determination of carbaryl with p -aminophenol (PAP) in order to reduce the waste volume and to preserve the maximum analytical performance. The procedure, which was implemented employing a flow network obtained by nesting five, three-way solenoid valves controlled by means of a 386 microcomputer equipped with an electronic interface running software written in quick basic 4.5, provides a limit of detection of 26 μg l −1 , comparable to that obtained using a conventional flow injection (FIA) manifold and lower than that found by sequential injection analysi…

Quality based classification of gasoline samples by ATR-FTIR spectrometry using spectral feature selection with quadratic discriminant analysis

Abstract A chemometric approach has been developed for characterization of gasoline samples regarding their quality. Attenuated total reflectance – infrared spectrometric data were processed by genetic algorithm (GA) and successive projection algorithm (SPA) feature selection techniques, being employed as an initial step prior to apply a discriminative tool. It was aimed to classify the fuel samples according to their quality passed/failed data. Chemometric predictive procedures were developed using quadratic discriminant analysis (QDA) combined with GA and SPA as a feature subset and feature selection strategy. Results showed 93.3% and 95.6% accuracy for SPA-QDA and GA-QDA models respectiv…

Determination of the energetic value of fruit and milk-based beverages through partial-least-squares attenuated total reflectance-Fourier transform infrared spectrometry

Abstract The estimation of important nutritional parameters, such as carbohydrates content and energetic value (calories) in commercially available fruit juice and flavour milk shakes has been made by attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) using a partial-least-square (PLS) calibration approach. A highly heterogeneous population of 65 samples obtained from the Spanish market, covering fruit juices, flavour milk shakes and milk-added fruit juices was used. The spectral range and the size of the calibration set for building the PLS model have been evaluated. Considering a calibration set comprised of 27 samples, selected via hierarchical cluster analys…

Dispersive magnetic immunoaffinity extraction. Anatoxin-a determination.

Specific monoclonal antibodies were coupled with magnetic Sepharose-based beads and used, for the first time. The methodology was applied to preconcentrate anatoxin-a from water and the later determination by ion mobility spectrometry (IMS). Dispersive magnetic immunoaffinity (d-MagIA) extraction methodology provided a limit of detection of 0.02μgL-1 and a satisfactory precision with a relative standard deviation lower than 15%. Recoveries were evaluated at 0.5, 1.0 and 5.0μgL-1 anatoxin-a with quantitative values from 91 to 115%. Additionally, isobaric interferences with phenylalanine were completely avoided by the use of the developed d-MagIA extraction coupled to IMS determinations.

A green method for the determination of cocaine in illicit samples

Abstract Direct determination of cocaine in untreated seized samples has been made based on diffuse reflectance measurements of the near infrared (NIR) radiation through samples contained inside standard glass vials. The method used a series of previously analyzed samples, by the reference gas chromatography method, to build a partial least squares calibration model which was validated using an independent set of samples. The use of a general model for samples containing from 11.38% till 86.44% (w/w) cocaine was based on the use of spectral ranges from 12500.7 to 10128.6, 9339.8 to 6967.7 and 5388.3 to 4597.6 cm−1 with previous first derivative and vector normalization data pre-processing a…

Application of machine-vision techniques to fish-quality assessment

Abstract Machine vision is a non-destructive, rapid, economic, consistent and objective inspection tool and is also an evaluation technique based on image analysis and processing with a variety of applications. We review the use of machine vision and imaging technologies for fish-quality assessment. This review updates and condenses a representative selection of recent research and industrial solutions proposed in order to evaluate the general trends of machine vision and image processing in the visible range applied for inspection of fish and fish products. In order to determine freshness and composition, it is necessary to measure and to evaluate size and volume, to estimate weight, to me…

Lateral flow assays (LFA) as an alternative medical diagnosis method for detection of virus species: The intertwine of nanotechnology with sensing strategies

Viruses are responsible for multiple infections in humans that impose huge health burdens on individuals and populations worldwide. Therefore, numerous diagnostic methods and strategies have been developed for prevention, management, and decreasing the burden of viral diseases, each having its advantages and limitations. Viral infections are commonly detected using serological and nucleic acid-based methods. However, these conventional and clinical approaches have some limitations that can be resolved by implementing other detector devices. Therefore, the search for sensitive, selective, portable, and costless approaches as efficient alternative clinical methods for point of care testing (P…

Recent advances in surface plasmon resonance biosensors for microRNAs detection

miRNAs are a large family of non-coding RNAs which play important roles in translational and post-transcriptional regulation of gene expression and biological processes. Abnormal expression of miRNAs is related to the initiation and progression of different diseases which make them be promising candidates for early medical diagnostics. Thus, accurate detection of miRNAs has great significance for disorder diagnosis. Nevertheless, their intrinsic characteristics such as short sequence, low concentration and sequence homology challenge routine techniques. The detection assays need to be extremely sensitive and selective in small value of intricate RNA samples. Biosensor-based strategies have …

Authentication of protected designation of origin artichokes by spectroscopy methods

Abstract Artichoke samples with the protected designation of origin (PDO) ‘Alcachofa de Benicarlo’ were discriminated from those produced in other towns surrounding Valencia and Murcia, outside the PDO frame. Inductively coupled plasma (ICP-OES), near infrared (NIR) and X-ray fluorescence (XRF) were assayed in order to achieve a correct sample classification of the three different origin sample groups (Benicarlo, Valencia and Murcia). Chemometrics was used to compare the ability of classification of artichoke from their origin by using concentration data of mineral elements, determined by ICP-OES, NIR spectra and XRF spectra. Multivariate analysis tools, as principal component analysis (PCA…

Direct determination of benzene in gasoline by flow-injection Fourier transform infrared spectrometry

Abstract A Fourier transform infrared spectrometric procedure for the automated determination of benzene in gasoline was developed, based on the use of flow-injection analysis. The method permits the direct determination of benzene without any pretreatment of samples, with a limit of detection of 0.02% (v/v) and a relative standard deviation of ca. 1% [for five independent analyses of a diluted sample containing a 0.4% (v/v) of benzene]. Results found by direct analysis agreed with those obtained by off-line and on-line standard addition methods. A rapid quality control procedure was developed, based on the on-line injection of gasoline samples (diluted 1 + 9 in hexane) into a carrier strea…

Recent advances on HIV DNA vaccines development: Stepwise improvements to clinical trials.

According to WHO (World Health Organization) reports, more than 770,000 people died from HIV and almost 1.7 million people becoming newly infected in the worldwide in 2018. Therefore, many attempts should be done to produce a forceful vaccine to control the AIDS. DNA-based vaccines have been investigated for HIV vaccination by researches during the recent 20 years. The DNA vaccines are novel approach for induction of both type of immune responses (cellular and humoral) in the host cells and have many advantages including high stability, fast and easy of fabrication and absence of severe side effects when compared with other vaccination methods. Recent studies have been focused on vaccine de…

Assessing air quality inside vehicles and at filling stations by monitoring benzene, toluene, ethylbenzene and xylenes with the use of semipermeable devices

BTEX (benzene, toluene, ethylbenzene, and xylenes) were used as target molecules to evaluate the quality of air inside motor vehicles and near filling stations, using semipermeable membrane devices (SPMDs) as low-cost passive sampling devices. A direct, fast, simple methodology based on the use of headspace-gas chromatography-mass spectrometry detection (HS-GC-MS) was developed for BTEX determinations, without any sample pre-treatment. SPMDs (25.4 cm2 surface, filled with 100 microL triolein) were employed as static samplers. After the selected deployment time, the SPMDs were heated inside a HS vial at 150 degrees C for 20 min and BTEX compounds were determined by GC-MS in selected ion moni…

Portability in analytical chemistry: a green and democratic way for sustainability

International audience; Recent advances in portability of analytical equipment have been considered to enlighten the advantages offered by portable instrumentation on greening the analytical methods. Their use drastically reduces sampling, sample stockage, and transport, thus avoiding environmental side effects and risks, also improving decision-making. The fact that portable instrumentation is, in general, less expensive than bench instruments and apparatuses makes also available the analytical tools for extended sectors of the population, thus making accessible the advantages derived from analytical methods. The role of sensor technology and portable miniaturized systems has been consider…

The social responsibility of environmental analysis

Abstract A literature updated has been made on the academical studies focused on the social impact of environmental studies, paying attention to both, the quality of the information provided and the side effects of the methodology employed, also considering the importance of the analytical methodologies in the development of remediation processes and the key subject of the transmission of the environmental information to the policy makers and the general society.

Non-chromatographic speciation of toxic arsenic in fish

Abstract A rapid, sensitive and economic method has been developed for the direct determination of toxic species of arsenic present in fish and mussel samples. As(III), As(V), dimethylarsinic acid (DMA), and monomethylarsonic acid (MMA) were determined by hydride generation–atomic fluorescence spectrometry using a series of proportional equations without the need of a chromatographic previous separation. The method is based on the extraction of arsenic species from fish through sonication with HNO3 3 mol l−1 and 0.1% (m/v) Triton and washing of the solid phase with 0.1% (m/v) EDTA, followed by direct measurement of the corresponding hydrides in four different experimental conditions. The li…

Targeted cancer therapy through antibody fragments-decorated nanomedicines.

Active targeting in cancer nanomedicine, for improved delivery of agents and diagnose, has been reviewed as a successful way for facilitating active uptake of theranostic agents by the tumor cells. The application of a targeting moiety in the targeted carrier complexes can play an important role in differentiating between tumor and healthy tissues. The pharmaceutical carriers, as main part of complexes, can be polymeric nanoparticles, micelles, liposomes, nanogels and carbon nanotubes. The antibodies are among the natural ligands with highest affinity and specificity to target pharmaceutical nanoparticle conjugates. However, the limitations, such as size and long circulating half-lives, hin…

Analysis of ecstasy in oral fluid by ion mobility spectrometry and infrared spectroscopy after liquid-liquid extraction.

We developed and evaluated two different strategies for determining abuse drugs based on (i) the analysis of saliva by ion mobility spectrometry (IMS) after thermal desorption and (ii) the joint use of IMS and infrared (IR) spectroscopy after liquid-liquid microextraction (LLME) to enable the sensitivity-enhanced detection and double confirmation of ecstasy (MDMA) abuse. Both strategies proved effective for the intended purpose. Analysing saliva by IMS after thermal desorption, which provides a limit of detection (LOD) of 160μgL(-1), requires adding 0.2M acetic acid to the sample and using the truncated negative second derivative of the ion mobility spectrum. The joint use of IMS and IR spe…

Fast extraction of cannabinoids in marijuana samples by using hard-cap espresso machines

Abstract A simple, quick and low cost procedure was developed for the extraction of Δ9-tetrahydrocannabinol, cannabidiol, and cannabinol from marijuana samples, based on the use of a hard-cap espresso extraction with 2-propanol. After extraction, cannabinoids were directly determined after appropriate dilution by gas-chromatography-mass spectrometry, reaching a limit of detection from 0.03 to 0.05 mg g−1. Extraction efficiency was evaluated by the comparison of results obtained for seized samples by the proposed method and a reference methodology based on ultrasound-assisted extraction. Moreover, ion mobility was proposed for the rapid and sensitive determination of Δ9-tetrahydrocannabinol …

Multicommutation ATR-FTIR: determination of sodium alpha-olefin sulfonate in detergent formulations

Abstract The mechanization of attenuated total reflectance measurements (ATR) in Fourier Transform Infrared spectrometry (FTIR) through the use of multicommutation has been evaluated in order to reduce the sample consumption and waste generation also avoiding risks of cells breaking. A new multicommutation ATR-FTIR procedure has been proposed for the determination of sodium alpha-olefin sulfonate (AOS) in liquid detergent formulations. The main advantages of this method are the low consumption of sample (96 ml per 100 determinations) and the analytical throughput (23 h −1 versus 15 h −1 for the manual mode). Results obtained for reference samples containing 7.52% to 9.52% (w/w) of AOS are i…

Air monitoring of selected volatile organic compounds in wineries using passive sampling and headspace-gas chromatography–mass spectrometry

Abstract Volatile compounds released during the production of wine at different steps of the winemaking process were evaluated using semipermeable membranes based passive samplers. Preliminary data on the differences between five wine varieties were provided together with the indoor quality of air to which winery workers are exposed during their professional activity. A simple, green and fast analytical methodology was employed for the direct analysis of deployed samplers by using head space (HS) gas chromatography–mass spectrometry (GC–MS) without any sample pre-treatment and avoiding the use of solvents. Terpenes as styrene, pinene, p-cymene and limonene were found at concentration levels…

Flow-Injection Solid Phase Partial Least-Squares Spectrophotometric Simultaneous Determination of Iron, Nickel and Zinc

A PLS-2 multivariate calibration method has been developed for the simultaneous determination of iron, nickel and zinc in ternary mixtures by solid phase spectrophotometry associated with flow injection analysis. Fe(II), Ni(II) and Zn(II) form color complexes with 1-(2-thiazolylazo)-2-naphthol (TAN), immobilized on a C18 bonded silica support, at pH 6.4. The proposed procedure is based on the different reaction/retention ratios of the studied ions on the solid support. Bilinear spectrophotometric data of the analytes, fixed in the solid support, were recorded in the 400-800 nm wavelength range as a function of time and a partial least squares (PLS-2) algorithm was used to predict results of…

On-line bidirectional electrostacking of chromium(III) and chromium(VI) for flame atomic absorption spectrometry determination

Abstract An on-line bidirectional electrostacking-flow injection-flame atomic absorption spectrometry method has been developed for the simultaneous separation, pre-concentration and determination of Cr(III) and Cr(VI). The electrostacking-flow injection unit was established, the pH and components of the support buffer and sample medium were investigated. Results indicated that the ionic mobility, electric field strength and sample area cross-section are the main influence factors on the electrostacking. The calibration range for both, Cr(III) and Cr(VI), was from 20 to 400 μg l −1 . The limit of detection was 7 μg l −1 for three-times the standard deviation of blank values using a electros…

The use of utraviolet-visible spectrophotometry in the determination of average properties of nonylphenol ethylene oxide condensates

Ultraviolet spectrophotometry is usd in the determination of average molecular weight (M), average degree of polymerization (X), the hydrophilic-lipophilic balance (HLB) and ethylene oxide percentage of nonylphenol ethylene oxide condensates. The method is based on determination of the absorptivity a, expressed in g lt-1 cm−1, from the absorbances measured at 275 nm for a series of dilutions of an aqeuous ethanolic solution (60:40, v/v/) of a given product, followed by numerical interpolation of this value in the expression a = f(HLB), log a = f(log M), and log a = f(log X). These expressions are obtained from reference samples or samples previously analyzed. The proposed method gives relat…

Retention of carbaryl by polyether type polyurethane foam: a critical study

This paper reports the retention of carbaryl by polyether type polyurethane foam in a dynamic mode. Several parameters that can influence the extraction of carbaryl from water samples were investigated such as concentration of carbaryl, mass of sorbent in the column, sample pH, saline concentration, solvent washing and sample flow rate. Results show that it is possible to achieve quantitative extractions when the sample flow rate is maintained up to 2.4 mL min−1, a mass of foam of 300 mg and a sample volume of 30 mL in 0.5 NaCl are employed. They also indicate that there is an ether-like solvent extraction mechanism controlling the sorption of the substance by the foam. Some recovery tests …

Education in Green Analytical Chemistry

Chemical and mineralogical analyses on stones from Sagunto Castle (Spain)

Abstract For the first time, an archaeometric study was carried out on the carbonate rock ashlars of the Sagunto Castle. The studied site is one of the most important and best preserved Spanish archaeological and architectural monuments, characterized by different construction phases from the Roman period to Modern Ages. Forty samples collected from thirteen different structures of Sagunto Castle and two quarries, located in the Sagunto's hill were used for comparative purposes. The samples were analyzed by X-ray diffraction, X-ray fluorescence and inductively coupled plasma mass spectrometry to determine their mineralogical and elemental composition. The obtained data show similar chemical…

Microwave-assisted saponification of animal greases for cholesterol determination

Abstract An alternative method for the hydrolysis of cholesterol esters in animal grease samples has been developed. The method consists of the microwave-assisted treatment of 4 g of animal fat or oil with 40 ml of an ethanolic KOH solution inside a 115 ml closed reactor in which samples were irradiated for 2.5 min at 50% power level of an exit power of 700 W. After extraction with petroleum ether and dissolution of the unsaponifiables in toluene, total cholesterol was determined spectrophotometrically by using p-anisidine as a test reagent of the enzymatic reaction of cholesterol through a bienzymic reactor in which cholesterol oxidase and horseradish peroxidase were noncovalently immobili…

New cut-off criterion for uninformative variable elimination in multivariate calibration of near-infrared spectra for the determination of heroin in illicit street drugs.

A new cut-off criterion has been proposed for the selection of uninformative variables prior to chemometric partial least squares (PLS) modelling. After variable elimination, PLS regressions were made and assessed comparing the results with those obtained by PLS models based on the full spectral range. To assess the prediction capabilities, uninformative variable elimination (UVE)-PLS and PLS were applied to diffuse reflectance near-infrared spectra of heroin samples. The application of the proposed new cut-off criterion, based on the t-Students distribution, provided similar predictive capabilities of the PLS models than those obtained using the original criteria based on quantile value. H…

Flow injection Fourier transform infrared determination of nicotine in tobacco

A fully automated procedure is proposed for the Fourier transform infrared (FTIR) determination of nicotine in tobacco. The method is based on the on-line extraction of nicotine with CHCl3. Samples, weighed inside empty extraction cartridges, were humidified with NH3 and the cartridges were installed in a flow manifold in which they were extracted with 2 ml CHCl3 for 2 min, then 400 microliters of the extract were introduced into a micro-flow cell using a carrier of CHCl3 and the IR spectrum was registered continuously. The absorbance, in the wavenumber range 1334-1300 cm-1, was measured, obtaining a peak as a function of time. The area of this peak was interpolated on a calibration line es…

Recent progress in optical and electrochemical biosensors for sensing of Clostridium botulinum neurotoxin

Abstract Botulinum toxin is a neurotoxic protein which produced from Clostridium botulinum and related species and it block acetylcholine release from presynaptic nerve terminals at the neuromuscular junctions. This toxin is life threatening for millions of people and growing menace to society since causing human botulism. Enzymatic activity of Botulinum neurotoxin within the cell made it hazardous and lead to flaccid paralysis. However, there isn't any reliable and precise remedy for this toxin. Therefore, there is an urgent need for early detection of this toxin in a fast and meticulous way with a robust and cost-effective relationship for real-time monitoring of Botulinum neurotoxin. Sev…

Direct determination of Mancozeb by photoacoustic spectrometry

Abstract A solvent free, fast and environmentally friendly photoacoustic-infrared-based methodology (PAS-FTIR) was developed for the determination of Mancozeb in agrochemicals. This methodology was based on the direct measurement of the transmittance spectra of solid samples and a multivariate calibration model to determine the active ingredient concentration. The proposed partial least squares (PLS) model was made using nine standards prepared by mixing different amounts of kaolin and Mancozeb, with concentrations between 5.43 and 88.10% (w/w). A hierarchical cluster analysis was made in order to classify the samples in terms of similarity in the PAS-FTIR spectra. From their spectra differ…

Towards an automatic lab-on-valve-ion mobility spectrometric system for detection of cocaine abuse.

A lab-on-valve miniaturized system integrating on-line disposable micro-solid phase extraction has been interfaced with ion mobility spectrometry for the accurate and sensitive determination of cocaine and ecgonine methyl ester in oral fluids. The method is based on the automatic loading of 500μL of oral fluid along with the retention of target analytes and matrix clean-up by mixed-mode cationic/reversed-phase solid phase beads, followed by elution with 100μL of 2-propanol containing (3% v/v) ammonia, which are online injected into the IMS. The sorptive particles are automatically discarded after every individual assay inasmuch as the sorptive capacity of the sorbent material is proven to b…

A validated and fast procedure for FTIR determination of Cypermethrin and Chlorpyrifos.

Abstract A FTIR methodology has been developed for the simultaneous determination of Cypermethrin and Chlorpyrifos in pesticide commercially available formulations. The method involves the extraction of both active principles with CHCl3 and direct measurement of the peak area values between 1747 and 1737 cm−1 corrected with a baseline defined at 2000 cm−1 for Cypermethrin and peak height values established at 1549 cm−1 corrected using a baseline situated at 1650 cm−1 for Chlorpyrifos. The limits of detection achieved were of the order of 0.7 and 0.4% (w/w), and the relative standard deviation 0.4 and 0.2% for Cypermethrin and Chlorpyrifos, respectively. The developed procedure provided stat…

New perspectives in the use of semipermeable membrane devices as passive samplers.

This review shows the state of the art, from 2000 to nowadays, of the use of semipermeable membrane devices (SPMDs) for monitoring persistent organic pollutants in both, air and aquatic environments. Since their first use in 1990, SPMDs have been employed for many environmental purposes, like air and water pollution monitoring. We have focussed the study in three subjects: (i) novel compounds accumulated by SPMDs, (ii) modifications of SPMDs to improve their specific uptake properties and (iii) alternatives in sample pre-treatment for the determination of pollutants accumulated in SPMDs.

Simultaneous determination of acetylsalicylic acid and caffeine in pharmaceuticals by flow injection with fourier transform infrared detection.

Abstract A fast quality control methodology has been developed for the simultaneous determination of acetylsalicylic acid (ASA) and caffeine in pharmaceuticals by flow injection—Fourier Transform Infrared Spectrometry. The method is based on the solubilization of ASA and caffeine in CH2Cl2 and the use of a flow system to introduce samples and standards in the spectrometer. Two solutions, containing 90 and 110% of the reported concentration of the two active principles in the sample, were employed in order to control the extreme tolerance levels accepted by the International Pharmacopeia for the composition of formulations. A 300 μl volume of each solution was injected in turn, into a carrie…

On-Capillary Surface-Enhanced Raman Spectroscopy: Determination of Glutathione in Whole Blood Microsamples.

Oxidative stress monitoring in the neonatal period supports early outcome prediction and treatment. Glutathione (GSH) is the most abundant antioxidant in most cells and tissues, including whole blood, and its usefulness as a biomarker has been known for decades. To date, the available methods for GSH determination require laborious sample processing and the use of sophisticated laboratory equipment. To the best of our knowledge, no tools suitable for point-of-care (POC) sensing have been reported. Surface-enhanced Raman spectroscopy (SERS), performed in a microvolume capillary measurement cell, is proposed in this study as a robust approach for the quantification of GSH in human whole blood…

Analytical techniques for the determination of bismuth in solid environmental samples

Abstract Bismuth is a trace element of the Earth’s crust, which is becoming environmentally significant. Although bismuth has relatively low toxicity, it can form characteristic intracytoplasmatic inclusions. This article illustrates the increasing need for fast pre-treatment techniques and highly sensitive detection methods for accurate measurements of bismuth at extremely low concentrations in solid environmental matrices.

Green aspects, developments and perspectives of liquid phase microextraction techniques.

Determination of analytes at trace levels in complex samples (e.g. biological or contaminated water or soils) are often required for the environmental assessment and monitoring as well as for scientific research in the field of environmental pollution. A limited number of analytical techniques are sensitive enough for the direct determination of trace components in samples and, because of that, a preliminary step of the analyte isolation/enrichment prior to analysis is required in many cases. In this work the newest trends and innovations in liquid phase microextraction, like: single-drop microextraction (SDME), hollow fiber liquid-phase microextraction (HF-LPME), and dispersive liquid-liqu…

Basic Chemometric Tools

Abstract The authentication of protected designation of origin and other protected geographical indications for foods involves the need for a deep knowledge of these kinds of samples and the correct identification of appropriate markers that are suitable to be used for authentication purposes. For this, significance tests must be developed and applied to provide evidence in a fast and accurate way; from this, it seems clear that advances in analytical tools, to obtain data regarding food chemical composition, and chemometric data treatments must be continued to provide to the users powerful identification methodologies. In this sense, the objective must be to differentiate between foods pro…

Smart Sorption Materials in Green Analytical Chemistry

The use of smart materials as alternative sorption materials for their use in greening sample preparation has been reviewed. It has been taking into consideration recent advances on the use of natural products, without any modification or purification, for making analyte extraction and pre-concentration and the use of specific materials in solid-phase extraction (SPE) and solid-phase microextraction (SPME) approaches. Inorganic materials, such as metal oxides, alumina-based, silica-based, and carbon-based materials together with biomimetic sorbents such as classical immunosorbents, aptamers, and molecularly imprinted polymers, have been reviewed as examples of these materials, stressing the…

Off-line coupling of multidimensional immunoaffinity chromatography and ion mobility spectrometry: A promising partnership.

The extreme specificity of immunoaffinity chromatography (IAC) columns coupled to the high sensitivity of ion mobility spectrometry (IMS) measurements makes this combination really useful for rapid, selective, and sensitive determination of a high variety of analytes in different samples. The capabilities of the IAC-IMS coupling have been highlighted under three different scenarios: (i) multiclass residue analysis using a single IAC column, (ii) multiclass residue analysis using stacked IAC columns, and (iii) isomer analysis. In the first case, the determination of three strobilurin fungicides - azoxystrobin, picoxystrobin, and pyraclostrobin - in water and strawberry juice was considered, …

Origin based classification of crude oils by infrared spectrometry and chemometrics

Abstract Crude oil samples from different Iranian petrol resources in both, raw and mixture forms have been characterized by attenuated total reflectance mid infrared spectroscopy. Obtained spectra were classified by chemometric techniques to propose a method for geological based classification of crude oil samples. Totally 251 samples from 7 petrol fields and 3 mixtures were analyzed. Mean centering and principal component analysis (PCA) supported – leverage value based outlier detection were used as preprocessing approaches. PCA, cluster analysis and soft independent modeling of class analogy (SIMCA) were utilized to classify the spectra. Obtained results confirmed that SIMCA is a robust …

Prediction of alkaline earth elements in bone remains by near infrared spectroscopy.

An innovative methodological approach has been developed for the prediction of the mineral element composition of bone remains. It is based on the use of Fourier Transform Near Infrared (FT-NIR) diffuse reflectance measurements. The method permits a fast, cheap and green analytical way, to understand post-mortem degradation of bones caused by the environment conditions on different skeletal parts and to select the best preserved bone samples. Samples, from the Late Roman Necropolis of Virgen de la Misericordia street and En Gil street located in Valencia (Spain), were employed to test the proposed approach being determined calcium, magnesium and strontium in bone remains and sediments. Coef…

Nanomaterial-based molecularly imprinted polymers for pesticides detection: Recent trends and future prospects

Abstract Pesticides have been widely used in agricultural and industrial production to prevent pests. So, sensing pesticides with high selectivity and sensitivity level plays a significant role in food safety management. Molecularly imprinted polymer (MIP) based sensors overcome the current restriction of traditional detection approaches and offer great potential for efficient, low-cost and low detection limit using smart miniaturized equipment. But some drawbacks could come from the lack of electrocatalytic activity and conductivity of MIPs that restrict their utilization in the sensing field. The integration of NPs with MIPs has opened new ways for rapid screening and monitoring of pestic…

Freshness assessment of gilthead sea bream (Sparus aurata) by machine vision based on gill and eye color changes

Abstract The fish freshness was evaluated using machine vision technique through color changes of eyes and gills of farmed and wild gilthead sea bream ( Sparus aurata ), being employed lightness ( L * ), redness ( a * ), yellowness ( b * ), chroma ( c * ), and total color difference (Δ E ) parameters during fish ice storage. A digital color imaging system, calibrated to provide accurate CIELAB color measurements, was employed to record the visual characteristics of eyes and gills. The region of interest was automatically selected using a computer program developed in MATLAB software. L * , b * , and Δ E of eyes increased with storage time, while c * decreased. The a * parameter of fish eyes…

Microwave-assisted distillation of iodine for the indirect atomic absorption spectrometric determination of iodide in milk samples

To complete these microwave distillation studies, a method for iodide determination in milk-type samples is proposed. The iodide contained in the sample is oxidized to iodine, which is distilled by means of microwave energy and reduced back to iodide. This iodide is combined with Hg(II) and 2,2′-dipyridyl to give an ion pair, which is selectively extracted into IBMK. Mercury is determined in the extract by ETAAS in order to determine iodide. The yield of the distillation process (100%) was evaluated using the Sandell–Kolthoff reaction. In addition, for the solvent extraction, no buffer was needed; 3/5 was the best phase ratio (organic/aqueous); 30 s was the shaking time and the extracts wer…

Electrochemical biosensors for glucose based on metal nanoparticles

Abstract Nanotechnology has affected almost all aspects of biomedicine. The integration of nanomaterials has contributed to the selectivity, the versatility, the stability and especially the sensitivity of bioelectronic devices, including biosensors. In this field, nanomaterials have been employed as enzyme immobilizers, enzyme stabilizers, surface modifiers or labeling factors or have provided individualized catalytic effects. Among other sensing platforms, glucose biosensors are of special clinical and industrial significance because of their role in monitoring blood-glucose levels in diabetes mellitus, one of the most prevalent metabolic disorders worldwide. Similar to other sensing plat…

Gold nanoprobe-based detection of human telomerase reverse transcriptase (hTERT) Gene Expression

Human Telomerase Reverse Transcriptase (hTERT) gene is expressed in all types of cancers, and it is considered as unique biomarker for early detection, monitoring and prognosis of different cancers. Routinely, the main techniques for detection of hTERT gene expression are based on enzymatic amplifications which need specified equipments, expert personnel and high cost and time. With regarding to the clinical importance of analysis of hTERT gene expression, we have developed a rapid, simple and low cost method which detects hTERT RNA target in 5 $\mu {\rm l}$ reaction scale using gold nanoprobes. The method is based on the inhibition of nanoparticle aggregation in the presence of ${\rm MgCl}…

Authentication of the protected designation of origin horchata de Valencia through the chemometric treatment of mineral content

Spanish horchata de chufa samples were authenticated based on the determination of mineral elements by inductively coupled plasma atomic emission spectrometry (ICP-OES) combined with different chemometric methods. The ability of multivariate analysis, such as principle components analysis (PCA), classification and regression trees (CARTs) and discriminant analysis (DA) were evaluated in order to achieve a correct sample classification. It was possible to clearly differentiate homemade and long-life commercial samples by all three methods and CART and DA provided an excellent tool to establish the growth origin of the tiger nuts. CART analysis employed the concentration of Mg to discriminate…

Mineral content of seasonings, salt and vinegar

Determination of sulfide in waters by flow-injection solid phase spectrophotometry

A highly sensitive flow injection solid-phase spectrophotometric method was developed for the determination of sulfide in waters. The method is based on the formation of Methylene Blue (MB) by reaction between sulfide and N,N-dimethyl-p-phenylenediamine chloride in presence of Fe(III) in acidic medium. The MB formed was adsorbed on C18 bonded silica, located inside a laboratory-made flow cell, which was placed in the optical path of the spectrophotometer. Analyte retention and detection at 666 nm were performed simultaneously, followed by elution with a mixture of methanol and hydrochloric acid. Several variables of the system, such as amine concentration, acidity of the reaction medium, re…

Poisoning histories in the Italian renaissance: The case of Pico Della Mirandola and Angelo Poliziano.

Giovanni Pico della Mirandola and Angelo Poliziano were two of the most important humanists of the Italian Renaissance. They died suddenly in 1494 and their deaths have been for centuries a subject of debate. The exhumation of their remains offered the opportunity to study the cause of their death through a multidisciplinary research project. Anthropological analyses, together with documentary evidences, radiocarbon dating and ancient DNA analysis supported the identification of the remains attributed to Pico. Macroscopic examination did not reveal paleopathological lesions or signs related to syphilis. Heavy metals analysis, carried out on bones and mummified tissues, showed that in Pico's…

Study of passive sampling of polycyclic aromatic hydrocarbons in gas phase using Amberlite XAD resins as filling materials of semipermeable membranes

Abstract In this work, a study was performed to evaluate the use of Amberlite XAD resins (XAD-2, XAD-4 and XAD-16), for the first time, as filling materials for low-density polyethylene membranes, which will be inserted as passive samplers for polycyclic aromatic hydrocarbons (PAHs) in gas phase. The use of samplers deployed for 48 h evidenced a relative capability to retain the compounds under study. A detailed study was performed to evaluate the recovery of analytes from the sampler through microwave-assisted extraction by using acetonitrile. A clean-up step using alumina-C18 cartridges was necessary before determination of the PAHs by high performance liquid chromatography with fluoresce…

HPLC determination of oxadiazon in commercial pesticide formulations

A simple, fast and precise high performance liquid chromatographic (HPLC) procedure has been developed for the determination of oxadiazon in emulsifiable concentrated pesticide formulations. 20 µL of diluted sample in acetonitrile were injected in a Kromasil C18 (250 ×am injetados em uma coluna Kromasil C18 4.6 mm, 5 µm) column, using acetonitrile:water (80:20) as mobile phase at 1 mL min-1 flow rate and oxadiazon determined by absorbance measurement at 292 nm. A theoretical limit of detection of 0.02 µg mL-1, a limit of quantification of 0.047 µg mL-1, corresponding to a 0.02 and 0.07% m/v in the original sample, and a relative standard deviation of 0.08% for three replicate analysis of sa…

Mineral profile of Spanish commercial baby food.

Commercial baby foods are an important part of the daily intake of babies from 6 to 12 months. The mineral profile of commercial baby foods in Spain was determined to establish levels of essential and non-essential elements, and their contribution to adequate intake (AI) and estimated average requirement (EAR). Thirty-five jars of commercial foods containing meat, fish, vegetables and fruit were obtained from the Spanish market and the mineral composition determined for 14 elements. In general, the baby foods analysed were sufficient for an adequate mineral intake, but contributions to AI and EAR for iron, zinc and calcium were very low (5-20%, 10-60% and 10-70%, respectively). This deficie…

Ion mobility spectrometry evaluation of cocaine occupational exposure in forensic laboratories

An approach, based on ion mobility spectrometry (IMS) has been developed for the control of cocaine in air of the breathing zone of operators, in laboratory surfaces and in nasal mucus of employees to evaluate cocaine exposure in a forensic laboratory. The analytical methodology has been validated in terms of accuracy, precision and limits of detection and results obtained were statistically comparable with those obtained by liquid chromatography. Cocaine concentration in laboratory air increases from 100 ± 35 ng m(-3) of a normal day to 10,000 ng m(-3) during the manipulation of cocaine seizures. The occupational exposure limit (OEL) for cocaine has not been established which difficult the…

Biochemical sensors: The state of the art

The basic components of a (bio)chemical sensor and the main concepts involved in the (bio)chemical sensor methodology are considered in order to depict the state of the art of the development of research in this field, paying special attention to the evolution of the published scientific literature in analytical chemistry.

Electrochemical nano-immunosensing of effective cardiac biomarkers for acute myocardial infarction

Abstract This review provides an overview of the various types of electrochemical immunosensors that have been developed for determination of cardiac biomarkers, along with significant advances over the last several years in related technologies. We also summarize the latest developments in the applications of electrochemical immunosensors in ultrasensitive detection of electroactive cardiac biomarkers.

Green extraction techniques in green analytical chemistry

Abstract Green analytical chemistry concept, involving the development of analytical methodologies with an environmental concern, encourages the use of direct analysis to avoid any sample treatment that involves energy and reagent consumption and generation of wastes. However, the determination of target analytes at trace concentration levels or in complex matrices frequently requires previous extraction, pre-concentration, or clean-up steps offering thus, additional possibilities for greening classical methods. So, a green evaluation of alternative extraction techniques to currently used ones for the extraction of solid, liquid, and gaseous samples has been carried out in this study. Moreo…

Iron and iron-oxide magnetic nanoparticles as signal-amplification elements in electrochemical biosensing

Abstract Growing demands for ultrasensitive biosensing have led to the development of numerous signal-amplification strategies. Based on their unique properties (i.e., electro-conductivity, bio-compatibility and ease of synthesis), various iron magnetic nanoparticles (MNPs) have proved to be an excellent nanomaterial for applications in electrochemical biosensing. This review shows how iron MNPs have made significant contributions in the development of electrochemical nanobiosensors, including immuno-, enzyme, DNA and aptamer types. More importantly, we discuss in detail different aspects of the electrochemical biosensors (e.g., modes of magnetic particles, detection techniques, analytes an…

Cytosensing of cancer cells using antibody-based molecular imprinting: A short-review

Abstract Rapid and effective differentiation between normal and cancer cells is an important objective for the diagnosis, prognosis and theranosis of tumors. This short review highlights some of the most recent developments on the application of molecular bioimprinting in detection of cancer cells using antibody-based cancer cell recognition method. The particular emphasis of this review is on sample-to-answer devices and approaches that enable down-stream investigation of the properties of the cells. Given the speed, portability, sensitivity and selectivity achieved using molecular bioimprinting technology on cancer cell monitoring, these methods hold the promise of transformative change i…

Determination of caffeine in tea samples by Fourier transform infrared spectrometry

A sustainable and environmentally friendly procedure has been developed for the FTIR determination of caffeine in tea leaf samples. The method is based on the extraction with ammonia and CHCl3 and direct determination of caffeine on the chloroform extracts using peak height absorbance measurements at 1658.5 cm(-1) and external calibration. The method provides a sensitivity of 0.2142 absorbance units mg(-1) mL and a limit of detection of 1 mg L(-1), corresponding to 0.002% m/m caffeine in tea leaves. As compared with a reference procedure, based on UV absorbance measurement at 276 nm after low pressure column chromatography, the developed procedure reduces the consume of CHCl3 by a factor of…

Carbon based nanomaterials for the detection of narrow therapeutic index pharmaceuticals

Precise detection of important pharmaceuticals with narrow therapeutic index (NTI) is very critical as there is a small window between their effective dose and the doses at which the adverse reactions are very likely to appear. Regarding the fact that various pharmacokinetics will be plausible while considering pharmacogenetic factors and also differences between generic and brand name drugs, accurate detection of NTI will be more important. Current routine analytical techniques suffer from many drawbacks while using novel biosensors can bring up many advantages including fast detection, accuracy, low cost with simple and repeatable measurements. Recently the well-known carbon Nano-allotrop…

Solid sampling Fourier transform infrared determination of Mancozeb in pesticide formulations

Abstract A series of approaches have been assayed for FTIR determination of Mancozeb in several solid commercial fungicides using different calibration strategies. The simplest procedure was based on the use of the ratio between the absorbance of a characteristic band of Mancozeb and that of a KSCN internal standard measured in the FTIR spectra obtained from KBr pellets. It was employed the quotient between peak height absorbance values at 1525 cm−1 for Mancozeb and 2070 cm−1 for KSCN. In these conditions a precision as relative standard deviation (RSD) of 0.6% and a relative accuracy error of 0.8% (w/w) were found. For complex formulations, containing other compounds with characteristic ab…

Determination of total arsenic in soft drinks by hydride generation atomic fluorescence spectrometry

Abstract A highly sensitive and simple method has been developed for the determination of total arsenic, by continuous hydride generation and atomic fluorescence spectrometry (HGAFS), in refreshing drink samples as colas, teas and fruit juices. Samples were mixed with concentrated HCl and KI to obtain final concentrations of 2 mol l−1 and 1%, respectively. These solutions were aspirated and merged with a reducing NaBH4 3% (m/v) solution, with sample and NaBH4 flow rates of 12.5 and 1.5 ml min−1, respectively. The hydride generated in a 170 cm reaction coil was transported to the detector with an Ar flow of 400 ml min−1. The recovery values of added concentrations, from 0.1 to 0.9 ng ml−1, o…

The Use of Amberlite Adsorbents for Green Chromatography Determination of Volatile Organic Compounds in Air

Passive samplers have been widely used for volatile organic compounds determination. Following the green chemistry tendency of the direct determination of adsorbed compounds in membrane-based devices through using head space direct chromatography analysis, this work has evaluated the use of Amberlite XAD-2, XAD-4, and XAD-16 adsorbents as a filling material for passive samplers. Direct analysis of the membranes by HS-GC-MS involves a solvent-free method avoiding any sample treatment. For exposed membranes, recoveries ranged from 10% to 203%, depending on the compound and adsorbent used. The limit of the detection values ranged from 1 to 140 ng per sampler. Acceptable precision and sensitivi…

Analytical Research Based on the Use of Low Cost Instrumentation

A multicommutated flow system for determination of bismuth in milk shakes by hydride generation atomic fluorescence spectrometry incorporating on-line neutralization of waste effluent

Abstract A highly sensitive method was developed for determination of bismuth in milk shakes by multicommutation hydride generation atomic fluorescence spectrometry (HG-AFS) based on off-line sonication for 10 min with aqua regia 8% (v/v) and on-line waste treatment. The instrumentation and chemistry variables were studied in order to provide the best performance. The limit of detection in the original samples, established for a probability level of 99.6% (k = 3), was 1.67 ng/g Bi. The method provides a fast alternative in control analysis with a sampling throughput of 72 h as compared with 31 h obtained by the classical continuous measurement. Additionally, multicommutation reduces waste g…

Multielemental determination of trace mineral elements in seawater by dynamic reaction cell inductively coupled plasma- mass spectrometry after Al(OH)3 coprecipitation

Abstract A simple method has been developed for the simultaneous determination of 12 trace mineral elements in seawater using, in some cases, several target isotopes (51V, 52Cr, 55Mn, 58,60Ni, 59Co, 63,65Cu, 64,66,68Zn, 75As, 78Se, 111,113Cd, 206,207,208Pb y 238U) in seawater. The method combined a simple and fast Al(OH)3 co-precipitation method, to pre-concentrate mineral elements and to separate them from the seawater matrix, and inductively coupled plasma mass spectrometry using the dynamic reaction cell with NH3 gas to do quantitative determinations free from polyatomic interferences. The recoveries of trace elements after Al(OH)3 co-precipitation varies between 80% for 111Cd and 116% f…

Nanosized hydrophobic gels: Advanced supramolecules for use in electrochemical bio- and immunosensing

Abstract Nanosized hydrogels have emerging as versatile supramolecules materials with application in various electrochemical biosensing devices. This review reports a systematic study of the usefulness of nano-sized hydrogels in the different steps of the process of development of electrochemical biosensing systems. The advantages offered by nano-sized hydrogels in detection of analytes are illustrated with representative recent examples that highlight the scientific interest in widening the use of hydrogel nanoparticles in electrochemical biosensing methods. In this review, different types of hydrogel nanoparticles-based electrochemical biosensors, such as enzyme, protein, and nucleic acid…

A passive sampling-based analytical strategy for the determination of volatile organic compounds in the air of working areas.

Abstract An analytical methodology based on the use of a polyethylene layflat tube filled with activated carbon and Florisil (ACFL-VERAM) was employed for the passive sampling of volatile organic compounds (VOCs) in the air of working areas of packing industries. VOCs amount in the ACFL-VERAM sampler was directly determined through head-space-gas chromatography–mass spectrometry (HS-GC–MS) allowing a direct determination in only 20 min without the need of any previous treatment. Uptake parameters, like sampling rate ( R S ) and sampler–air partition coefficient ( K SA ), were determined for every studied VOC from adsorption isotherm data. Additionally, experimental equations have been propo…

First‐Derivative Fourier‐Transform Infrared Determination of Oxadiazon in Commercial Herbicide Formulations

Abstract A Fourier‐transform infrared (FTIR) method has been developed for the quantification of oxadiazon in herbicide formulations. The method involves the extraction of the active ingredient by sonication of the samples with CHCl3 and direct measurement of the peak area values in first‐order derivate spectra from 1770 cm−1 to 1774 cm−1 corrected with a baseline point located at 1950 cm−1 and after a 5‐point smoothing. A limit of detection (3 s) of 0.03 mg g−1 and a typical relative standard deviation (RSD) of 1.3% were found. Results obtained were comparable with those found by liquid chromatography with UV detection. The proposed method involves a 7‐times reduction in solvent consumptio…

Hard Cap Espresso Machines in Analytical Chemistry: What Else?

A hard cap espresso machine has been used in combination with liquid chromatography with molecular fluorescence detection for the determination of polycyclic aromatic hydrocarbons (PAHs) from contaminated soils and sediments providing appropriate extraction efficiencies and quantitative results. Naphthalene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benz[a]anthracene, chrysene, benz[b]fluoranthene, benz[k]fluoranthene, benz[a]pyrene, dibenz[a,h]anthracene, benz[ghi]perylene, and indeno[1,2,3-cd]pyrene were used as target compounds. It should be mentioned that the pairs benz[a]anthracene-chrysene and dibenz[a,h]anthracene-benz[ghi]perylene peaks coelute under th…

Infrared biospectroscopy for a fast qualitative evaluation of sample preparation in metabolomics.

Liquid chromatography-mass spectrometry (LC-MS) has been increasingly used in biomedicine to study the dynamic metabolomic responses of biological systems under different physiological or pathological conditions. To obtain an integrated snapshot of the system, metabolomic methods in biomedicine typically analyze biofluids (e.g. plasma) that require clean-up before being injected into LC-MS systems. However, high resolution LC-MS is costly in terms of resources required for sample and data analysis and care must be taken to prevent chemical (e.g. ion suppression) or statistical artifacts. Because of that, the effect of sample preparation on the metabolomic profile during metabolomic method d…

Selection of calibration set samples in determination of olive oil acidity by partial least squares–attenuated total reflectance–Fourier transform infrared spectroscopy

Abstract A chemometric method has been applied for the determination of the free fatty acid (FFA) concentration in commercial olive oil samples of different types an origins by using Fourier transform infrared spectroscopy (FTIR) attenuated total reflectance (ATR) measurements. Different methods for selecting the training set, including hierarchical cluster analysis, were applied and compared. The prediction capabilities of partial least squares (PLS) multivariate calibration methods, net analyte signal (NAS) preprocessing followed by PLS or classical least squares (CLS) regression method of ATR–FTIR data were evaluated. Several aspects, like spectral range to be considered, different prepr…

Three independent channel nanohybrids as fluorescent probes

A properly designed pyrene-capped CdSe/ZnS nanohybrid can act as a three-channel fluorescent sensor due to the independent emission of the pyrene monomer and excimer as well as that of the nanoparticle. As proof of principle, it was tested for a simple and rapid quantification of TNT in the presence of interferents of the same chemical family.

A clean method for flow injection spectrophotometric determination of cyclamate in table sweeteners

Abstract A flow system based on the multicommutation is proposed for fast and clean determination of cyclamate. The procedure exploits the reaction of cyclamate with nitrite in acidic medium and the spectrophotometric determination of the excess of nitrite by iodometry. The flow system was designed with a set of solenoid micro-pumps to minimize reagent consumption and waste generation. The detection limit was estimated as 30 μmol L −1 (99.7% confidence level) with linear response ranging up to 3.0 mmol L −1 . The coefficient of variation was estimated as 1.7% for a solution containing 2.0 mmol L −1 cyclamate ( n  = 20). About 60 samples can be analyzed per hour, consuming only 3 mg KI and 1…

Sensing Chiral Drugs by Using CdSe/ZnS Nanoparticles Capped withN-Acetyl-L-Cysteine Methyl Ester

Chiral quantum dots (QDs), differing in their core or shell size and, consequently, in their optical properties, were synthesized by the treatment of commercially available amine-capped quantum dots with methyl ester N-acetyl-L-cysteine (CysP). Interestingly, their colloidal methanol solutions remain stable for several months. Their NMR and IR spectra were in accordance with CysP binding to the QD surface through two anchoring groups; its thiolate (strongly bound) and the carbonyl group of its ester (weaker bound) group, whereas their circular dichroism (CD) spectra showed a new broad redshifted band, suggesting that the attachment to the QD surface modified the conformational equilibrium t…

Improvement of the atomic fluorescence determination of mercury by using multicommutation

Atomic fluorescence spectrometry (AFS) determination of Hg has been improved by exploiting the possibilities of the multicommutation approach in order to outline a fully mechanised system which supplies the same sensitivity as the use of continuous measurements, reducing drastically the reagents consumed and waste generation. The use of multicommutation with a simultaneous reduction of the liquid–gas separator volume and the insertion point modification of argon transport gas provides a sensitivity of the AFS measurements of 300 mV ng−1 ml (using a full scale of 1000 mV), a limit of detection (3 s) of 1.3 ng l−1 and relative standard deviation values below 0.1% for 10 independent measuremen…

Atomic fluorescence determination of total and inorganic arsenic species in beer

A simple and nearly direct procedure has been developed for the determination of As in beers, based on hydride generation and atomic fluorescence detection. Using 2 mol l−1 HCl with a carrier flow of 6 ml min−1, 3% m/v NaBH4 with a flow of 1.3 ml min−1, a reaction coil of 200 cm and an argon flow of 400 ml min−1, total arsenic in beer could be determined in samples diluted 1∶10 with a final concentration of 2 mol l−1 HCl, 1% m/v KI and 0.08% v/v of an antifoam agent. For the estimation of AsIII and AsV concentrations in beer samples, the difference between the analytical sensitivities of the fluorescence signals obtained for As hydride, without and with previous treatment of samples with KI…

Early stage diagnosis of programmed cell death (apoptosis) using electroanalysis: Nanomaterial and methods overview

Timely monitoring of apoptosis can effectively assist early diagnosis of related diseases and continuous evaluation of the efficacy of drugs. Therefore, developing advanced methods for apoptosis evaluation has attracted more and more attention. In addition, the increased demand for understanding the early stages of apoptosis is pushing the envelope for solutions in early instance real-time monitoring of death kinetics. In this review, various types of electro-analytical methods for detection of apoptosis were discussed. The emphasis is placed in diagnosis of apoptosis based on cyto-, immune-, geno-, apta-, and peptide based biosensing strategies. In the first part of review, various electro…

Feature selection strategies for quality screening of diesel samples by infrared spectrometry and linear discriminant analysis.

Abstract A rapid approach has been developed for the characterization of diesel quality, based on attenuated total reflectance – Fourier transform infrared (ATR-FTIR) spectrometry, which could be useful for diagnosing the sample quality condition. As a supervised technique, linear discriminant analysis (LDA) was employed to process the spectrometric data. The role of variable selection methods was also evaluated. Successive projection algorithm (SPA) and genetic algorithm (GA) feature selection techniques were applied prior to the discriminative procedure. It was aimed to compare the effect of feature selection procedures on classification capability of IR spectrometry for the diesel sample…

Monitoring of microRNA using molecular beacons approaches: Recent advances

Abstract Micro ribose nucleic acid (miRNA) recognition is of remarkable significance in the investigation of its functions as well as diagnosis of various diseases. The significance of miRNA itself is owing to the complex regulatory roles in several physiological processes and its close association with important diseases such as cardiovascular problems, diabetes, Alzheimer's disease and different kinds of cancers. On the other hand, there are numerous challenges to conquer in the recognition of miRNA, consisting of low abundance, varied concentration range, small size, prolonged extraction process from cells and sequence resemblances. Traditional approaches for miRNA recognition do not mee…

A portable and low cost equipment for flow injection chemiluminescence measurements.

A compact, reliable and low cost flow injection chemiluminescence system is described. The flow system consists of a set of solenoid micro-pumps that can dispense reproductive micro-volumes of solutions. The luminometer was based on a coiled cell constructed from polyethylene tubing that was sandwiched between two large area photodiodes. The whole equipment costs about US$ 750 and weights ca. 3 kg. Equipment performance was evaluated by measuring low concentrations of hydrogen peroxide by oxidation of luminol and for the determination of ammonium, based on its inhibition of the luminescence provided by the reaction of luminol and sodium hypochlorite. Linear responses were achieved within 1.…

Sweeteners determination in table top formulations using FT-Raman spectrometry and chemometric analysis

Abstract A partial least squares (PLS) Fourier transform Raman spectrometry procedure based on the measurement of solid samples contained inside standard glass vials, has been developed for direct and reagent-free determination of sodium saccharin and sodium cyclamate in table top sweeteners. A classical 22 design for standards was used for calibration, but this system provides accuracy errors higher than 13% w/w for the analysis of samples containing glucose monohydrate. So, an extended model incorporating glucose monohydrate (23 standards) was assayed for the determination of sodium saccharin and sodium cyclamate in all the samples. Mean centering spectra data pre-treatment has been emplo…

Surface plasmon resonance signal enhancement based on erlotinib loaded magnetic nanoparticles for evaluation of its interaction with human lung cancer cells

Abstract Surface plasmon resonance (SPR) sensor provides a very useful tool based on its label-free, real-time monitoring and low price properties. However, measurement of small molecules and extremely diluted analytes is difficult and therefore, signal enhancement is required. In the present study, signal enhancement of erlotinib conjugated magnetic nanoparticles (erlotinib-MNPs) compared to erlotinib was evaluated via their interaction with overexpressed epidermal growth factor receptor on human lung cancer cells (A549 cell line) surface using SPR sensor at three temperature levels. The attained results showed an average signal amplification of about 2.5-fold for MNP-erlotinib interaction…

Current advancement in electrochemical analysis of neurotransmitters in biological fluids

Abstract Analysis of neurotransmitters is useful for the diagnosis of central nervous system diseases. This review gives a general view of recent advances in the development of electrochemical sensors for detection/determination of neurotransmitters. The purpose of the review is to provide useful insights in terms of ( a ) choice of materials, ( b ) methods/techniques preferably applied, ( c ) immobilization procedures, and ( d ) other practical aspects. Following an introduction into the field, we give a short account on the principle and general types of electrochemical sensors, and then treat sensing methods for neurotransmitters. It is subdivided into sections on ( i ) Dopamine ( ii ) A…

Ultrasonic nebulization inductively coupled plasma optical emission spectrometry method for wine analysis

Abstract A methodology was developed to determine mineral elements in wines using Inductively Coupled Plasma Optical Emission Spectrometry combined with ultrasonic nebulization. The concentration of 36 elements (Al, B, Ba, Bi, Ca, Cd, Ce, Co, Cr, Dy, Er, Eu, Fe, Gd, K, La, Lu, Mg, Mn, Mo, Na, Nd, Ni, Pb, Pr, Sb, Sc, Sm, Sr, Tb, Ti, Tm, V, Y, Yb, and Zn) was determined in 59 wine samples and used to distinguish between Brazilian and Spanish wines. The best conditions for the plasma were selected using a two-level factorial design: radiofrequency power 1500 W; plasma gas flow rate 15 L min−1; auxiliary 0.70 L min−1; and nebulizer 0.40 L min−1. An exploratory multivariate analysis by Principal…

Future Perspectives on the Use of Smart Materials

Hard cap espresso extraction and liquid chromatography determination of bioactive compounds in vegetables and spices

Abstract A new analytical procedure, based on liquid chromatography with diode array and fluorescence detection, has been proposed for the determination of bioactive compounds in vegetables and spices after hard cap espresso extraction. This novel extraction system has been tested for the determination of capsaicin and dihydrocapsaicin from fresh chilli and sweet pepper, piperine from ground pepper, curcumin from turmeric and curry, and myristicin from nutmeg. Extraction efficiency was evaluated by using acetonitrile:water and ethanol:water mixtures. The proposed method allows the extraction of samples with 100 mL of 60% (v/v) ethanol in water. The obtained limits of quantification for the …

Chemometric determination of lipidic parameters in serum using ATR measurements of dry films of solvent extracts

Attenuated total reflectance (ATR) infrared spectroscopy of dried organic extracts of serum samples has been evaluated as a fast method for the determination of triglycerides, cholesterol, high density lipoprotein (HDL) and low density lipoprotein (LDL). After careful selection of solvents based on green parameters, serum samples were extracted using hexane-isopropanol and ethyl acetate-ethanol mixtures. Microscopy studies and comparison with standard spectra were performed in order to investigate whether the proposed methodology is suitable for the quantification of lipids in serum samples. The results of these preliminary studies confirmed that the variations in the IR spectra of sample e…

Use of semipermeable membrane devices for monitoring pesticides in indoor air.

Abstract In this work, 40 pesticides from different categories were analyzed in the air of 20 indoor places that have an intensive use of pesticides. Passive sampling was carried out by using semipermeable membrane devices (SPMDs) deployed for 7 days. SPMDs were analyzed using microwave-assisted extraction and GC/MS. PCB-195 was used as an internal standard. Recoveries ranged between 81 and 108 for many compounds, with RSD values <11. Typical LOD values for 7 days of sampling were from 0.1 to 3.1 ng/m. Propamocarb, propoxur, carbosulfan, pirimicarb, metribuzin, metalaxyl, pendimethalin, oxadiazon, phenothrin, and permethrin were detected in 11 sampling sites, with air concentrations …

Mineral Profile

The identification of foods with protected designation of origin (PDO) has been a long-standing issue. Its detection provides valuable information to regulatory commissions (government and industries) which can regulate precise quality control procedures for their products. Authentication of food covers many different aspects, including characterization, mislabelling and misinformation regarding origin, and adulteration, which is defined as the process to reduce the quality or nature of a given substance by adding a foreign or an inferior substance and removing a vital element. Numerous methods have been developed as fingerprinting methodologies for PDO products. The analytical techniques c…

Mineral content of eggs

Flow injection Fourier transform infrared determination of caffeine in coffee

Abstract A fully automatized procedure has been developed for the Fourier transform infrared (FT-IR) spectroscopic determination of caffeine in coffee samples. The method involves the on-line extraction of caffeine with CHCl3. Samples, weighed inside empty PTFE cartridges of 0.5 cm internal diameter (i.d.) and 1.5 ml volume, were humidified with four drops of 0.25 M NH3. The cartridge was installed in a flow manifold, in which samples were extracted in a closed-flow system with 1 ml CHCl3 during 6 min. Four hundred microliters of the extract were introduced in a microflow cell and absorbance measured as a function of time at 1659 cm−1, with a baseline established between 1900 and 830 cm−1, …

Headspace-Liquid Phase Microextraction for Attenuated Total Reflection Infrared Determination of Volatile Organic Compounds at Trace Levels

A combination of headspace (HS) sampling and liquid phase microextraction (LPME) has been successfully developed to solve sensitivity problems in attenuated total reflection (ATR) infrared determination of volatile organic compounds (VOCs). The HS sampling facilitates the selective extraction of the target volatile analytes from the sample matrix, while the liquid phase microextraction allows their preconcentration prior to infrared analysis. The direct determination of extracted analytes in the acceptor solvent provides high preconcentration factors of the order of 200 with a reduced consumption of organic solvents and a minimum generation of wastes, being thus the developed methodology a …

Portable microwave assisted extraction: An original concept for green analytical chemistry.

International audience; This paper describes a portable microwave assisted extraction apparatus (PMAE) for extraction of bioac-tive compounds especially essential oils and aromas directly in a crop or in a forest. The developed procedure, based on the concept of green analytical chemistry, is appropriate to obtain direct in-field information about the level of essential oils in natural samples and to illustrate green chemical lesson and research. The efficiency of this experiment was validated for the extraction of essential oil of rosemary directly in a crop and allows obtaining a quantitative information on the content of essential oil, which was similar to that obtained by conventional m…

Use of semipermeable membrane devices for assessment of air quality in Tangier (Morocco)

Semipermeable membrane devices (SPMDs) have been used for the evaluation of the contamination of air in both the urban and the industrial area in Tangier (Morocco). Benzene, toluene, ethylbenzene a...

Nano-materials for use in sensing of salmonella infections: Recent advances

Salmonella infectious diseases spreading every day through food have become a life-threatening problem for millions of people and growing menace to society. Health expert's estimate that the yearly cost of all the food borne diseases is approximately $5-6 billion. Traditional methodologies for salmonella analysis provide high reliability and very low limits of detection. Among them immunoassays and Nucleic acid-based assays provide results within 24h, but they are expensive, tedious and time consuming. So, there is an urgent need for development of rapid, robust and cost-effective alternative technologies for real-time monitoring of salmonella. Several biosensors have been designed and comm…

Determination of cyromazine in pesticide commercial formulations by vibrational spectrometric procedures

Two vibrational spectrometry-based methodologies were developed for Cyromazine determination in solid pesticide formulations: a Fourier transform infrared (FTIR) procedure, based on the extraction of Cyromazine by CH3OH and direct determination in the extracts by peak height measurement at 1622 cm−1 corrected using a baseline defined at 1900 cm−1, and a FT-Raman determination, made directly on the powdered solid products using standard chromatographic glass vials as sample cells and measuring the Raman intensity between 633 and 623 cm−1 for a baseline established between 663 and 601 cm−1. The sensitivity obtained was 0.01631 absorbance g−1 mg for FTIR determination and 2.23 area values g−1 …

Combination of mid- and near-infrared spectroscopy for the determination of the quality properties of beers

Abstract The combination of infrared (MIR) and near-infrared (NIR) spectroscopy has been employed for the determination of important quality parameters of beers, such as original and real extract and alcohol content. A population of 43 samples obtained from the Spanish market and including different types of beer, was evaluated. For each technique, spectra were obtained in triplicate. In the case of NIR a 1 mm pathlength quartz flow cell was used, whereas attenuated total reflectance measurements were used in MIR. Cluster hierarchical analysis was employed to select calibration and validation data sets. The calibration set was composed of 15 samples, thus leaving 28 for validation. A critic…

Pyrene-Capped CdSe@ZnS Nanoparticles as Sensitive Flexible Oxygen Sensors in Non-Aqueous Media**

A flexible, highly sensitive sensor of oxygen in non-aqueous solvents is described. It consists of CdSe/ZnS nanoparticles decorated with a considerable number of pyrene units, thus making the formation of the pyrene excimer possible. The emission of the pyrene excimer and that of the nanoparticle are suitably separated from each other and also from the excitation wavelength. This sensor can be applied as a ratiometric oxygen sensor by using the linear response of the pyrene excimer lifetime combined with the linear response of the nanoparticle excited state lifetime. This nanohybrid has been assayed in seven media with different dielectric constants and viscosities over the whole oxygen con…

FT-Raman determination of Mepiquat chloride in agrochemical products

Abstract A fast and environmentally friendly procedure has been developed for Fourier transform Raman (FT-Raman) determination of a quaternary ammonium compound, Mepiquat chloride, in pesticide emulsifiable concentrate formulations. The method is based on the measurement of peak area values between 711 and 701 cm −1 corrected using a baseline defined at 620 cm −1 and interpolated in an external calibration of Mepiquat chloride standards dissolved in water. FT-Raman spectra were collected over 1.5 min from samples confined in screw cap standard chromatographic glass vials, at a nominal resolution of 4 cm −1 accumulating 25 scans per spectra and using a laser power of 1000 mW. Five commercial…

Green determination of the presence of volatile organic compounds in vehicle repair shops through passive sampling.

A simple, fast and green direct analytical methodology has been developed to evaluate the concentration level of volatile organic compounds (VOCs) in indoor areas of vehicle repair shops using membrane devices as passive samplers. VOCs retained in the samplers were directly determined without any sample pre-treatment and avoiding the use of solvents by head space (HS) coupled to gas chromatography-mass spectrometry (GC-MS) in only 20 min. Benzene, toluene, tetrachloroethene, m,p-xylene and o-xylene were found at concentration levels from 0.1 to 11.2 mg m(-3).

Solid-phase FT-Raman determination of caffeine in energy drinks

Abstract A solid-phase vibrational spectrometry-based methodology (solid-phase Fourier transform-Raman spectrometry, SP-FT-Raman) has been developed for caffeine determination in commercial energy drink samples. The Raman spectra of caffeine, fixed on a C18 solid phase packed into a glass tube of 5 mm i.d., was obtained directly between 3500 and 70 cm −1 . In order to quantify caffeine, Raman intensity between 573 and 542 cm −1 corrected using a baseline defined between 580 and 540 cm −1 was used. A repeatability of 3%, as relative standard deviation of five analysis of a 200 mg l −1 concentration, and a limit of detection of 18 mg l −1 were obtained. The SP-FT-Raman procedure provides a sa…

Early stage screening of breast cancer using electrochemical biomarker detection

Recently researchers have driven their attention in the development of biosensors for breast cancer detection using different biomarkers. This review reports a systematic study of the usefulness of marker-based electrochemical biosensors in breast cancer and its early diagnosis. Also, various types of electro-analytical methods for early stage screening of breast cancer were discussed. The emphasis is placed on immune-, geno- cyto- and enzyme-biosensing strategies. In addition, the advantages offered by some nano-materials in detection of breast cancer biomarkers are illustrated with representative recent examples that highlight the scientific interest in widening the use of new materials/m…

Recent advances in on-line solid-phase pre-concentration for inductively-coupled plasma techniques for determination of mineral elements

Abstract We provide a critical survey on recent progress in on-line solid-phase pre-concentration for inductively-coupled plasma (ICP)-based techniques for trace-level determination of metals. We highlight some of the useful solid-phase materials suitable for on-line separation and enrichment prior to ICP determination. We discuss different applications of the methods developed along with their analytical figures of merit. Finally, we sketch out future prospects in this field.

Cereals and pulses

Multicommutation Fourier transform infrared determination of benzene in gasoline

A fully mechanized method to determine benzene in motor gasolines has been developed based on the use of Fourier transform infrared spectroscopy (FT-IR) and multicommutation. The flow network comprised a set of three-way solenoid valves and was controlled by means of a microcomputer furnished with an electronic interface and running by a software written in QUICK BASIC 4.5. The flow network and control software were designed to implement the multicommutation approach providing facilities to handle sample and reagent solutions, so that, sample dilution, external calibration and standard addition could be easily performed on-line. The method permits the direct determination of benzene without…

Determination of non-steroidal anti-inflammatory drugs in water and urine using selective molecular imprinted polymer extraction and liquid chromatography

Abstract A selective solid-phase extraction was employed for the improvement of the determination of non-steroidal anti-inflammatory drugs (NSAIDs) in continental water and urine samples. Ketoprofen, naproxen, diclofenac, and ibuprofen were selected as target analytes due to they are the most frequently administered and consumed NSAIDs. These compounds were extracted using molecular imprinted polymers and determined by liquid chromatography with diode array (DAD), and tandem-mass spectrometry (MS–MS) detectors. Performance of DAD and MS–MS detectors was evaluated throughout this study. The obtained limits of quantification, after a 50-fold preconcentration solid-phase extraction, varied fro…

Advanced mechanotherapy: Biotensegrity  for governing metastatic tumor cell fate via modulating the extracellular matrix.

Mechano-transduction is the procedure of mechanical stimulus translation via cells, among substrate shear flow, topography, and stiffness into a biochemical answer. TAZ and YAP are transcriptional coactivators which are recognized as relay proteins that promote mechano-transduction within the Hippo pathway. With regard to healthy cells in homeostasis, mechano-transduction regularly restricts proliferation, and TAZ and YAP are totally inactive. During cancer development a YAP/TAZ - stimulating positive response loop is formed between the growing tumor and the stiffening ECM. As tumor developments, local stromal and cancerous cells take advantage of mechanotransduction to enhance proliferatio…

Development of a versatile, easy and rapid atmospheric monitor for benzene, toluene, ethylbenzene and xylenes determination in air

Abstract A new procedure for the passive sampling in air of benzene, toluene, ethylbenzene and xylene isomers (BTEX) is proposed. A low-density polyethylene layflat tube filled with a mixture of solid phases provided a high versatility tool for the sampling of volatile compounds from air. Several solid phases were assayed in order to increase the BTEX absorption in the sampler and a mixture of florisil and activated carbon provided the best results. Direct head-space-gas chromatography–mass spectrometry (HS-GC–MS) measurement of the whole deployed sampler was employed for a fast determination of BTEX. Absorption isotherms were used to develop simple mathematical models for the estimation of…

First-order derivative resolution of overlapped PAH peaks with common mass spectra in gas chromatography–mass spectrometry

Abstract First-order derivative of 15 points smoothed chromatograms of mixtures of benzo( b )fluoranthene (BbF) and benzo( k )fluoranthene (BkF) for the m / z 252 ion obtained using two microscans has been proposed as a simple alternative to the resolution of overlapped chromatographic peaks of these two compounds which have identical mass spectra. The procedure provides limits of detection of 12 and 29 ng g −1 for BbF and BkF, respectively and offers the possibility to use the 250 and 248 ions to confirm the identity of these analytes.

Variable selection for the determination of total polar materials in fried oils by near infrared spectroscopy

Total polar materials (TPM) content is considered as the best indicator and the most common parameter to check the quality of deep-frying oils. The development of simpler and quicker analytical techniques than the available methods to monitor oil quality in restaurants and fried food outlets is an important topic related to the human health. This paper reports a comparison of the variable selection of near infrared (NIR) spectra by multiple linear regression (MLR-NIR) with partial least squares (PLS-NIR) models for the quantification of TPM in fried vegetable oils. The use of PLS-NIR offers an alternative in laboratory bench equipment for the determination of TPM in oils employed for fryin…

Greening the wastes

Problems associated with analytical waste toxicity and waste treatment are reviewed in the frame of the water treatment, being collected a series of models, from the big-scale treatment of waste waters and adapted to the effluents generated during sample analysis. In fact to move from wastes to clean or no-contaminant wastes is a way from greening those methods in which any sample treatment and the use of reagents and solvents cannot be avoided. The last contributions in the field have been taken into account in this study and future trends have been proposed.

Advances in detection of fastidious bacteria: From microscopic observation to molecular biosensors

Abstract Identification of pathogens and diagnosis of infections are important health challenges, especially in the case of fastidious bacteria which are those difficult-to-grow. A fastidious organism is any organism that has a complex nutritional requirement. Additionally, a fastidious microorganism will only grow when specific nutrients are included in the culture medium. These bacteria can cause serious diseases whose detection and monitoring is critical in many cases. The oldest detection methods are based on simple microscopy observation and staining, after culture on selective growth media, but often do not provide a clear answer. Some new molecular approaches, such as DNA-based seque…

Challenges in Green Analytical Chemistry

Concerns about environmental pollution, global climate change and hazards to human health have increased dramatically. This has led to a call for change in chemical processes including those that are part of chemical analysis. The development of analytical chemistry continues and every new discovery in chemistry, physics, molecular biology, and materials science brings new opportunities and challenges. Yet, contemporary analytical chemistry does not consume resources optimally. Indeed, the usage of toxic chemical compounds is at the highest rate ever. All this makes the emerging field of green chemistry a “hot topic” in industrial, governmental laboratories as well as in academia. This book…

Metal-organic frameworks conjugated with biomolecules as efficient platforms for development of biosensors

Abstract Recent developments in the field of metal-organic frameworks (MOFs) have renewed the interests of scientists to bring about a major breakthrough in this field soon. These particles consist of ultra-highly porous and tremendous internal surface areas with extraordinary variabilities that make them highly potent compounds in nanomedicine. Moreover, low weight, large free volumes, and multiple functionalities of these particles have made them extremely attractive for various applications. Along with a critical role in the adsorption and separation of different analytes, they also have an immense role in the development of biosensor platforms that are expected to pave the way for accur…

Cold vapour atomic fluorescence determination of mercury in milk by slurry sampling using multicommutation

Abstract A highly sensitive mechanized method has been developed for the determination of mercury in milk by atomic fluorescence spectrometry (AFS). Samples were sonicated for 10 min in an ultrasound water bath in the presence of 8% (v/v) aqua regia, 2% (v/v) antifoam A and 1% (m/v) hydroxilamine hydrochloride, and after that, they were treated with 8 mmol l −1 KBr and 1.6 mmol l −1 KBrO 3 in an hydrochloric medium. Atomic fluorescence measurements were made by multicommutation, which provides a fast alternative in quality control analysis, due to the easy treatment of a large number of samples (approximately 70 h −1 ), and is an environmentally friendly procedure, which involves a waste ge…

Identification and determination of synthetic cannabinoids in herbal products by dry film attenuated total reflectance-infrared spectroscopy.

A new procedure has been developed for the identification and quantitative determination of synthetic cannabinoids in illicit herbal preparations. The methodology is based on the use of attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) measurement of sample extracts with 2-propanol drying 5µL of the extracts onto the ATR crystal. The qualitative identification was carried out on the 2-propanol extract after identification of the herbal matrix, followed by its subtraction and using a cut-off criterion of 75%. Quantitative determination was made by univariate calibration using the absorbance of the band located at 1520cm-1 of the spectrum. Four different cannabin…

Optical immunosensing of effective cardiac biomarkers on acute myocardial infarction

Abstract This review describes: • the advantages of examples of optical methods used in immunosensing of cardiac biomarkers and their reported applications, stressing their potential for future developments; • evaluation of some progress toward viable cardiac-biomarker measurements for detection and diagnostics of myocardial infarction; and, • trends in the development of optical immunosensors, including integrated immunosensors, and the application of nanotechnology and microfluidic technology.

Rapid on-line sample dissolution assisted by focused microwave radiation for silicate analysis employing flame atomic absorption spectrometry: iron determination.

An on-line automated flow injection system with microwave-assisted sample digestion was used to perform silicate rock dissolution in acid medium for iron determination. For this purpose, a continuous flow system was built up by using an automatic flow injection analysis (FIA) system coupled to a flame atomic absorption spectrometer (FAAS), including a focused microwave oven unit. Inside the microwave cavity was inserted a polytetrafluoroethylene (PTFE) reactor coil (300cm length and 0.8mm i.d.) where the dissolution takes place. Chemical and flow variables as well as iron determination parameters were studied. In the flow system, a slurry of the rock sample (50mg in 200ml of acid mixture HF…

Determination of pyrethroid insecticide residues in vegetable oils by using combined solid-phases extraction and tandem mass spectrometry detection

Abstract A methodology has been developed for the determination of pyrethroid insecticide residues in vegetable oils, based in a solid-phase extraction (SPE) with combined solid supports phases. Several solid phases such as florisil, alumina, C18 and graphitized carbon black were tested in order to minimize fat residues, being a combination of treated alumina and C18 which provided the best results. Oil samples were partitioned with acetonitrile–hexane (1:1) and then eluted through a combined column packed with deactivated basic-alumina and C18, employing the acetonitrile extract as elution solvent. Gas chromatography tandem mass spectrometry was used for determination. Tetramethrin, Bifent…

Mineral soil composition interfacing archaeology and chemistry

Abstract In the last decade, different soil types have been analysed to evaluate the effect of human activities from an archaeological point of view. In particular, in the last few years, tremendous advances have been made in sample preparation and analytical methods used in archaeological soil analyses. However, there is still a need to set standardized protocols to achieve different archaeological goals. Therefore, in this study, the analytical methods available to study archaeological soils have been reviewed together with a critical discussion on the challenging archaeological questions, which could be answered by determining their mineral composition. Data on trace elements and rare ea…

Literature survey of on-line elemental speciation in aqueous solutions.

The literature about the on-line speciation in water has been comprehensively studied. Critical examination of this subject reveals that a great deal of work has been performed in this area for inorganic metal species and some organic compounds. The topic studied mainly includes the speciation of chromium, selenium, copper, arsenic, lead, cadmium, mercury, iron, aluminium, nickel, tin, antimony, phosphorus, nitrogen and others. The present literature survey includes also comments about the possibilities and problems of speciation as a function of analytical steps, general strategies involved and methods proposed in the literature for each element or a series of elements.

A preliminary approach to mineral intake in the Spanish diet established from analysis of the composition of university canteen menus

Abstract The concentration of mineral elements in complete menus has in Spain been determined in order to establish the levels of essential and toxic elements and their contribution to the maximum recommended intake. Thirteen university canteen menus obtained from the Burjassot campus, in Valencia, were analysed to establish a first approach on mineral composition in the Spanish diet. The menus were composed of a mixture of cereals, meat, fish, vegetables, fruits and dairy products. Samples were crushed, homogenized and lyophilized, and 25 elements were determinated by inductively coupled plasma optical emission spectroscopy (ICP-OES) after digestion of samples in a microwave oven. Menu sam…

Development of a non-chromatographic method for the speciation analysis of inorganic antimony in mushroom samples by hydride generation atomic fluorescence spectrometry

Abstract A simple and sensitive method has been developed for the direct determination of toxic species of antimony in mushroom samples by hydride generation atomic fluorescence spectrometry (HG AFS). The determination of Sb(III) and Sb(V) was based on the efficiency of hydride generation employing NaBH 4 , with and without a previous KI reduction, using proportional equations corresponding to the two different measurement conditions. The extraction efficiency of total antimony and the stability of Sb(III) and Sb(V) in different extraction media (nitric, sulfuric, hydrochloric, acetic acid, methanol and ethanol) were evaluated. Results demonstrated that, based on the extraction yield and th…

Fourier transform infrared spectrometric strategies for the determination of Buprofezin in pesticide formulations

Abstract Two different strategies for Buprofezin determination, an off-line extraction and stopped-flow determination and an automated procedure, based on the on-line extraction of Buprofezin samples with chloroform and flowing action analysis–fourier transform infrared (FIA–FT-IR) spectrometric measurement of the extracts, have been developed. For the treatment of the off-line extraction mode, data a three-factor partial least squares (PLSs) calibration was developed, using the region from 1465.7 to 1342.3 cm−1 with a single point baseline defined at 2051.9 cm−1 and based on the use of chloroform solutions of Buprofezin. The method provides a R.S.D. On the other hand, the recommended FIA m…

Nondestructive Direct Determination of Heroin in Seized Illicit Street Drugs by Diffuse Reflectance near-Infrared Spectroscopy

A new method has been developed for the fast and nondestructive direct determination of heroin in seized street illicit drugs using partial least-squares regression analysis of diffuse reflectance near-infrared spectra. Data were obtained from untreated samples placed in standard glass chromatography vials. A heterogeneous population of 31 samples, previously analyzed by a reference method, was employed to build the calibration model and to have a separated validation set. Based on the use of zero-order data for a calibration set of 21 samples, after standard normal variate and quadratic linear removed baseline correction (detrending), in the wavelength range from 1111 to 1647 nm, 8 PLS fac…

Validated, non-destructive and environmentally friendly determination of cocaine in euro bank notes.

A non-destructive, fast and environmentally friendly procedure has been developed for cocaine determination in euro bank notes. Cocaine was extracted with 15 ml methanol by vortex agitation during 5 min. The extract was evaporated and reconstituted in 0.5 ml methanol. GC-MS-MS analysis was performed using as precursor ion m/z 182.2, with an excitation energy voltage of 1.60 eV, being the product ions measured m/z 150.2 and 82.0. A limit of detection of 0.15 ng per note and a repeatability of 6%, established from the relative standard deviation, of a 1 ng ml(-1) level, were achieved. Recoveries of 101+/-2 and 98+/-3% were obtained for samples spiked with 100 and 10 microg respectively. Resul…

Preconcentration of aluminium by micellar-enhanced ultrafiltration

Abstract Traces of aluminium were preconcentrated in water samples by forming a complex with lumogallion, and successfully accumulated in the micellar phase obtained from cationic or non-ionic surfactants and filtered through 10 000 molecular weight cut-off ultrafiltration membranes. Studies indicated that, at pH 5.9, with 1 X 10 −3 M lumogallion and 2 X 10 −2 M cetyltrimethylamonium bromide, quantitative retention of aluminium present at μg ml −1 concentration levels was achieved. A micellar-enhanced fluorimetric procedure was employed to analyse the permeate solutions, whereas nitrous oxide-acetylene flame atomic emission spectrometry was used to determine aluminium in the retentate. The …

Analysis of multi-source metabolomic data using joint and individual variation explained (JIVE).

Metabolic profiling is increasingly being used for understanding biological processes but there is no single analytical technique that provides a complete quantitative or qualitative profiling of the metabolome. Data fusion (i.e. joint analysis of data from multiple sources) has the potential to circumvent this issue facilitating knowledge discovery and reliable biomarker identification. Another field of application of data fusion is the simultaneous analysis of metabolomic changes through several biofluids or tissues. However, metabolomics typically deals with large datasets, with hundreds to thousands of variables and the identification of shared and individual factors or structures acros…

Evaluation of Flavonoid Derivative and Doxorubicin Effects in Lung Cancer Cells (A549) Using Differential Pulse Voltammetry Method.

Purpose: Electrochemical measurements have prompted the progress as a consequence of their affectability, cost-affectivity and comparatively short examination time. The aim of this study was the fast evaluation of the effect of chemotherapy compounds on the viability of lung cancer cells (A549) via electrochemical methods. Methods: Cyclic voltammetry (CV) was used as a primary method to distinguish between electrochemical behavior of normal and lung cancer cells. Differential pulse voltammetry (DPV) was employed as a complementary analyses method for the impact of doxorubicin (DOX) and Flavonoid modified drug (FMD) (US patent Application number: 62548886) on Lung cancer cells. Results: Only…

Dendrimer-encapsulated and cored metal nanoparticles for electrochemical nanobiosensing

Abstract We discuss nanosized dendrimers from the point of view of electrochemical-biosensor design. We review electrochemical biosensors based on dendrimer-encapsulated metal nanoparticles (NPs) and their various applications (e.g., measurement of small biological and toxic molecules, detection of DNA, and immunosensing of disease biomarkers). Finally, we discuss some future applications of electrochemical biosensors based on dendrimer-encapsulated metal NPs.

Utilisation de dérayures de cuir tanné au chrome pour la décontamination des eaux polluées par les colorants et les huiles

Abstract Les dérayures du cuir ont montré une grande capacité d'adsorption des colorants organiques directs. La capacité maximale de rétention est de 333,3 mg/g et de 312,5 mg/g respectivement pour les colorants DR75 et DR80. Un pH acide et une température de l'ordre de 50°C sont favorables à la décoloration. Les essais ont révélé la faisabilité de la décontamination d'un rejet de textile par les dérayures. Le taux d'épuration peut dépasser 90 p.100 dans des conditions précises de pH et de température. Les dérayures brutes et saturées par le colorant DR80 ont montré également une grande capacité d'absorption des huiles (5 à 6,5 g/g). En milieu aqueux, ces déchets fibreux réagissent fortemen…

Clean analytical method for the determination of propoxur

Abstract A method has been developed for the determination of propoxur, a carbamate pesticide, by means of its reaction with p-aminophenol (PAP). The method involves the reaction, in the presence of KIO4, between the quinoneimine form of PAP and the deprotonated form of 2-isopropoxyphenol, obtained by the alkaline hydrolysis of propoxur, to provide an indophenol dye which absorbs at 600 nm. The analysis is carried out in a flow system and, after the measurement step, the waste, the reaction product and the unreacted derivatising agent is detoxified in a UV-irradiated coil placed after the measurement flow-cell and after mixing the waste with a TiO2(anatase) catalyst slurry, which can be reu…

Metal speciation in biological fluids — a review

The literature on the speciation of metal ions in biological fluids is comprehensively reviewed. Critical examination on this subject reveals that major work has been done in blood and urine. Speciation in materials like milk has not yet been widely studied. On the other hand, only few references could be found on sweat, saliva, cell lysate, cerebrospinal, seminal, tear and bronchoalveolar fluids. The topics studied for these fluids were mainly the speciation of arsenic, mercury, aluminium and selenium. Work on the speciation of other elements like zinc, chromium, cadmium, lead, copper, iron etc. have also been carried out in such matrices. The present literature survey includes also a crit…

Nanomaterial-based cocaine aptasensors.

Up to now, many different methods have been developed for detection of cocaine, but most of these methods are usually time-consuming, tedious and require special or expensive equipment. Therefore, the development of simple, sensitive and rapid detection methods is necessary. In the last decade, aptamers have been used as a new biosensor platform for detection of cocaine in different samples. Aptamers are artificial single-stranded DNA or RNA oligonucleotides capable of binding to specific molecular targets with high affinity and if integrated to nanomaterials, it may lead in precise methods for cocaine detection in the common laboratories. In this review, recent advances and applications of…

An Overview of Green Analytical Techniques in the Spectrometric Analysis of Environmental and Biological Samples

ABSTRACT This literature survey presents in a nutshell different parameters for the effectiveness of the green spectrometric procedures, which have been applied to the determination of organics, inorganics, and metal ions in different matrices. The following issues were considered: the main aspects of miniaturization, reagent replacement, reduction of wastes, and on-line recovery and detoxification, which made the analytical procedures sustainable. Also, a discussion of analytical characteristics along with spectrometric methodologies and applications is included.

Evaluation of extraction alternatives for Fourier transform infrared spectrometric determination of oil and greases in water

Abstract Liquid-liquid extraction (LLE), solid phase extraction (SPE) and microwave-assisted extraction are evaluated for Fourier transform infrared (FTIR) spectrometric determination of oil and grease in polluted waters. A fast microwave-assisted quantitative procedure is proposed for the total extraction of oil and grease into CCl 4 from water samples, with an irradiation time of 1 min at an exit power of 520 W using closed PTFE vessels. The FTIR quantification of oil and grease is carried out by the measurement of the area under the absorbance spectra in the range between 3058 and 2780 cm −1 , with a baseline established between 3200 and 2700 cm −1 . The analytical features of the propos…

Comparison of near and mid infrared spectroscopy as green analytical tools for the determination of total polar materials in fried oils

Abstract Total polar materials (TPM) are used as an indicator of the quality in the frying oil because of high values may be harmful for human health. Spanish legislation establishes the maximum level of total polar materials for frying fats and oils for human consumption around 25% (w/w). Official methods to monitor oil quality are time consuming and use a lot of chemicals; therefore it is necessary a simple and quick analytical technique to evaluate fried oils. Transmittance near-infrared (NIR) and attenuated total reflection mid-infrared (ATR-MIR) spectroscopy measurements, combined with partial least squares (PLS) regression, offer alternatives to determine TPM in fried oils with relati…

Recent advances on aptamer-based biosensors to detection of platelet-derived growth factor.

Platelet-derived growth factor (PDGF-BB), a significant serum cytokine, is an important protein biomarker in diagnosis and recognition of cancer, which straightly rolled in proceeding of various cell transformations, including tumor growth and its development. Fibrosis, atherosclerosis are certain appalling diseases, which PDGF-BB is near to them. Generally, the expression amount of PDGF-BB increases in human life-threatening tumors serving as an indicator for tumor angiogenesis. Thus, identification and quantification of PDGF-BB in biomedical fields are particularly important. Affinity chromatography, immunohistochemical methods and enzyme-linked immunosorbent assay (ELISA), conventional m…

Vibrational spectroscopy in soil and sediment analysis

The literature concerning the use of vibrational spectroscopy for soil and sediment analysis, published in the last years, has been revised in order to provide a picture of the strengths and weaknesses of these direct techniques to characterize soil composition and properties. Many soil components as water, organic matter, like humic substances, and minerals, can be determined together with physicochemical parameters as pH, conductivity or redox potential. The main strategies to obtain sample spectra and to extract, as many as possible, useful information were evaluated, taking into account the progress on chemometrics and discussing the whole analytical process, from sampling to sample pre…

Recent advances on development of portable biosensors for monitoring of biological contaminants in foods

Abstract Background There is a demand for easy, rapid and affordable analysis of biological contaminants in foods to guarantee their safety and quality. Most analysis of food contaminants is commonly performed in a limited number of samples in centralized laboratories by an expert technician. Therefore, developing of alternative techniques such as portable biosensors is of great significance. Scope and approach This review aims to discuss the recent advances in designing and applying of portable biosensors for the detection of biological food contaminants including bacteria, fungi and the related toxins. Also, the review deals briefly the basic knowledge of various portable biosensors which…

FTIR approaches for diuron determination in commercial pesticide formulations.

Two strategies have been developed for Diuron determination by FTIR spectrometry, an off-line extraction and stopped-flow determination and a fully mechanized procedure, based on the on-line extraction of Diuron and FIA-FTIR measurement of the extracts. The aforementioned procedures have been compared with a reference chromatographic method. The off-line FTIR spectra were obtained at a nominal resolution of 4 cm(-1) from 4000 to 900 cm(-1) by accumulating 25 scans. Diuron was determined using peak height measurements at 1582 cm(-1) corrected using a baseline defined between 1562 and 1614 cm(-1). The waste generation of the off-line procedure was 3.4 mL chloroform for each sample, and the me…

Non-invasive analysis of solid samples

Within the Green Analytical Chemistry paradigm, the best alternative for greening the methods of analysis comprises the direct determination of sample composition and/or sample properties without any chemical sample treatment, and, of course, it would be preferable not to have any physical treatment before acquisition of the information desired. In this review, we evaluate the state of the art in, and available alternatives for, analysis of solids without prior sample treatment, starting from the non-invasive quality control of products or processes through to the use of portable instruments for in situ determinations and the development of methods based on image analysis. We evaluate the a…

Nanomaterials for use in immunosensing of carcinoembryonic antigen (CEA): Recent advances

Abstract This review (with 86 refs.) covers the state of the art in electrochemical and optical immunoassay of carcinoembryonic antigen (CEA). The purpose of the review is to provide useful insights in terms of (a) choice of materials, (b) methods/techniques preferably applied, (c) immunological procedures, (d) immobilization procedures, and (d) other practical aspects. Following an introduction into the field, we give a short account on the principle and general types of immunoassay, and then treat immunoassay for CEA. The first section covers nanomaterial based electrochemical immunoassay, with subsections on using of nanoparticles, hyperbranched polymers, graphene and their derivatives f…

Vibrational Spectrometry Strategies for Quality Control of Procymidone in Pesticide Formulations

Abstract Two vibrational spectrometry–based methodologies were developed for procymidone determination in wettable powdered pesticide formulations. The Fourier‐transform infrared (FTIR) procedure was based on the selective extraction of procymidone by chloroform and determination by peak area measurement between 1451 and 1441 cm−1, using a baseline correction established between 1490 and 1410 cm−1, and a precision of 0.4% and a limit of detection of 0.01% w/w procymidone for a sample mass of 25 mg were obtained. For FT‐Raman determination, the selected conditions were peak area measurement between 1005 and 995 cm−1 Raman shift, with a baseline correction fixed between 1030 and 947 cm−1, and…

Strategies for the rapid characterization of metals and organic pollutants in solid wastes and contaminated soils by using mass spectrometry

Abstract Hyphenated techniques involving mass spectrometry (MS) such as ICP-MS, GC–MS and LC–MS are the most powerful tools for both qualitative and quantitative characterization of metals and organic pollutants in previously dissolved or extracted samples. However a considerable analytical effort is required in developing simple and general sample preparation strategies for the complete characterization of toxic substances in solid wastes and soils. This article gives a critical review of the state-of-the-art and future perspectives for rapid procedures to evaluate the pollution of soils and sediments, also considering new alternatives like flow injection analysis–MS and direct sampling MS.

Peptide based biosensors

Abstract This review provides an overview of the various types of (bio)sensors based on peptides for their analytical use, along with significant advances over the last several years in related technologies. So, it will be described: i) principles in biosensing using peptides ii) aspects of fabrication in the perspective of (bio)sensing applications iii) potential of electrochemical, electrochemiluminescence, photoelectrochemical, and optical (bio)sensors for the determination of target analytes within sub-nanomolar range also discussing the main problems in (bio)sensing iv) multiplex electrochemical and optical (bio)sensors, both with and without labels. v) Latest developments in the appli…

Comprehensive analysis of airborne pesticides using hard cap espresso extraction-liquid chromatography-high-resolution mass spectrometry

A hard cap espresso extraction procedure has been developed to recover airborne pesticides in particulate matter trapped in filters. This extraction step was made for 20s at 72°C and 19bar using 50mL of 20% (v/v) acetonitrile in water. After that, based on NaCl salting out, extracts were concentrated 22 times and analysed by ultra-high performance liquid chromatography - high resolution mass spectrometry. 35 pesticides were evaluated, as a proof of concept, being validated the whole methodology and compared the extraction method with that based on microwave assisted extraction for 20min. In short, the method avoids cross-contamination of samples, it is relatively fast and consumes only 10mL…

Automated Fourier Transform near Infrared Determination of Buprofezin in Pesticide Formulations

An automated procedure has been developed for Fourier transform near infrared (FT-NIR) determination of buprofezin in pesticide formulations. This methodology is based on on-line pesticide extraction with acetonitrile from solid samples and its determination by using peak area absorbance measurements between 2147 and 2132 nm, corrected with a horizontal baseline established at 2091 nm. The repeatability, as a relative standard deviation of five independent analyses of 18.9 mg g−1 of buprofezin, was 0.06% and the limit of detection 5 mg L−1. The reagent consumption was clearly reduced compared with a chromatographic reference procedure from 40.4 mL acetonitrile per sample, required by high …

Determination of chromium(III) and chromium(VI) in mineral water by bidirectional electrostacking and electrothermal atomic absorption spectrometry

Abstract A feasibility investigation was carried out on the use of bidirectional electrostacking for simultaneous separation and pre-concentration of Cr(III) and Cr(VI) and their electrothermal atomic absorption spectrometry (ETAAS) determination. The bidirectional electrostacking manifold was improved, and the effects of sample tube cross-section and electrostacking time on the pre-concentration factor were investigated. Results indicate that the sample tube cross-section and electrostacking time are the main influence factors on the electrostacking pre-concentration, as well as the electric field strength and ionic mobility. The method developed was suitable for the simultaneous separatio…

Smart materials for sample preparation in bioanalysis: A green overview

Abstract The analysis of biological samples is a complex challenge due to the complexity of the matrix, but also to the low concentration of target analytes that must be determined. Consequently, different sample treatment procedures have been proposed in bioanalysis to clean-up and enrich sample extracts, paying special attention to microextraction approaches. In this frame, the combined use of microextraction approaches with smart materials provides environmentally friendly sample treatment strategies with improved selectivity, sensitivity, and reusability. Applications of smart solid materials includes antibody–antigen interaction based materials, aptamers, molecularly imprinted polymers…

Methods for the vibrational spectroscopy analysis of beers

The main possibilities and drawbacks of vibrational spectroscopy techniques, infrared (both in the middle and near infrared ranges) and Raman, for the analysis of beers have been reviewed taking into consideration methods proposed in the scientific literature for the determination of as many as possible compounds and parameters of beers. Details about the procedures available and comments on the future developments in this field have been based on the experience of authors and extended checking of the characteristics of the procedures published till now.

Comparison of transflection and transmission FTIR imaging measurements performed on differentially fixed tissue sections

The widespread and cost-effective use of transflection substrates in Fourier transform infrared (FTIR) imaging of clinical samples is affected by the presence of artefacts including the electric field standing wave (EFSW) and contributions from light dispersion. For IR-based diagnostics, the manifestation of undesirable artifacts can distort the spectra and lead to erroneous diagnosis. Nevertheless, there is no clear consensus in the literature about the degree of influence of these effects. The aim of this work is to contribute to this discussion by comparing transflection and transmission images of the same tissue. For this purpose two adjacent sections of the same tissue (lymphoma sample…

Speciation of chromium in natural waters by micropumping multicommutated light emitting diode photometry.

Abstract A simple and sensitive multicommutated flow procedure, implemented by employing a homemade light emitting diode (LED) based photometer, has been developed for the determination of chromium (VI) and total chromium in water. The flow system comprised a set of four solenoid micro-pumps, which were assembled to work as fluid propelling and as commutating devices. The core of the detection unit comprised a green LED source, a photodiode and a homemade flow cell of 100 mm length and 2 mm inner diameter. The photometric procedure for the speciation of chromium in natural waters was based on the reaction of Cr (VI) with 1,5-diphenylcarbazide. Cr (III) was previously oxidized to Cr (VI) and…

Use of reflectance infrared spectroscopy for monitoring the metal content of the estuarine sediments of the Nerbioi-Ibaizabal River (Metropolitan Bilbao, Bay of Biscay, Basque Country).

Multivariate partial least-squares (PLS) calibration models have been developed for the spatial and seasonal simultaneous monitoring of 14 trace elements (Al, As, Cd, Co, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Sn, V, and Zn) in sediments from 117 samples taken in the estuary of the Nerbioi-Ibaizabal River. Models were based on the chemometric treatment of diffuse reflectance near-infrared (NIR) and attenuated total reflectance (ATR) mid infrared (MIR) spectra, obtained from samples previously lyophilized and sieved with a particle size lower than 63 microm. Vibrational spectra were scanned in both, NIR and MIR regions. Developed PLS models, based on the interaction between trace elements and organic m…

Green direct determination of mineral elements in artichokes by infrared spectroscopy and X-ray fluorescence.

Near infrared (NIR) and X-ray fluorescence (XRF) spectroscopy were investigated to predict the concentration of calcium, potassium, iron, magnesium, manganese and zinc in artichoke samples. Sixty artichokes were purchased from different Spanish areas (Benicarlo, Valencia and Murcia). NIR and XRF spectra, combined with partial least squares (PLS) data treatment, were used to develop chemometric models for the prediction of mineral concentration. To obtain reference data, samples were mineralised and analysed by inductively coupled plasma optical emission spectrometry (ICP-OES). Coefficients of determination obtained for the regression between predicted values and reference ones for calcium, …

Mid- and near-infrared determination of metribuzin in agrochemicals

Abstract Two infrared-based methodologies were developed for metribuzin determination in pesticide formulations after extraction with acetonitrile. Fourier transform mid infrared (MIR) procedure was based on peak area measurements between 1692 and 1670 cm −1 corrected with a baseline fixed at 1877 cm −1 . Fourier transform near infrared (NIR) determination was made by measuring the peak area between 6498 and 6332 cm −1 corrected using a two points baseline defined between 6570 and 6212 cm −1 . Repeatability, as relative standard deviation, of 5 independent measurements at mg g −1 concentration level was 0.3% and 0.03% for MIR and NIR, respectively, and limit of detection values of 9 and 17 …

Quantitative Analysis, InfraredUpdate based on the original article by Frederic Cadet,Encyclopedia of Analytical Chemistry, © 2000, John Wiley & Sons, Ltd.

Determination of Paint Solvents by Vapour Phase Fourier Transform Infrared Spectrometry.

Abstract A fast procedure has been developed for the direct determination of paint solvents. The method is based on the injection of small volumes of untreated solvent mixtures into a heated Pyrex glass reactor in which the sample is volatilized and introduced by means of a flow of nitrogen into an IR multiple pass gas cell and the spectrum in the mid-IR region is registered as a function of time. Data found for samples are interpolated in calibration graphs obtained by injecting different volumes of pure compounds which constitute the solvent mixture. A methylisobutylketone (MIBK) toluene mixture was used as test system to develop the proposed procedure. The method provides a limit of dete…

Determination of antifreeze substances in the airport runoff waters by solid-phase microextraction and gas chromatography–mass spectrometry method

Abstract A new method has been developed for the determination of antifreeze agents such as ethylene glycol (EG), propylene glycol (PG), and diethylene glycol (DEG) in the samples of airport runoff water. The method is based on headspace solid–phase microextraction (HS–SPME) of target analytes, which is coupled with gas chromatography–mass spectrometry (GC–MS). Until now, there was a lack of appropriate methodology for collecting reliable data about the concentration levels of these toxic de/anti-icing substances in the new type of environmental samples such as the airport runoff water. The evaluation of green extraction technique, i.e., HS–SPME resulted in establishing the optimal extracti…

Non-invasive diagnosis of oral cancer: The role of electro-analytical methods and nanomaterials

Abstract Oral cancer is a kind of head and neck cancer and is each cancerous tissue growth located in the oral cavity. Non-invasive early diagnosis of oral cancer is the most effective means to reduce death from this disease or increase the survival time. In this review, various types of electro-analytical methods for detection of oral cancer were discussed. The emphasis is placed on non-invasive detection of oral based on immune-, geno-, cyto-, apta-, and enzyme-biosensing strategies. In the first part of review, various electrochemical immunosensing methods for the detection of common biomarker in oral cancer and examines their potential as a new method were discussed. In the second part …

Recent advances on thermosensitive and pH-sensitive liposomes employed in controlled release

Nanotechnology has recently gained lots of interest in drug delivery due to its potential to improve the therapeutic outcomes of various diseases. Particularly, a wide range of different nano-sized vesicles has been investigated for drug delivery. Among them, one of the most attractive and well-investigated nanocarriers are liposomes. Although liposomes have several advantages such as low toxicity, biodegradability and biocompatibility as well as accumulate in tumor site via enhanced permeability and retention (EPR) effect, inefficient drug delivery to the target cells could affect the therapeutic purpose of most of conventional liposomal formulations. Therefore, new systems of drug release…

A multicommuted stop-flow system employing LEDs-based photometer for the sequential determination of anionic and cationic surfactants in water

It has been developed an automatic stop-flow procedure for sequential photometric determination of anionic and cationic surfactants in a same sample of water. The flow system was based on multicommutation process that was designed employing two solenoid micro-pumps and six solenoid pinch valves, which under microcomputer control carry out fluid propelling and reagent solutions handling. A homemade photometer using a photodiode as detector and two light emitting diodes (LEDs) with emission at 470 nm (blue) and 650 nm (red) as radiation sources, which was tailored to allow the determination of anionic and cationic surfactants in waters. The procedure for anionic surfactant determination was b…

Flow-injection determination of water in organic solvents by near-infrared spectrometry

Abstract A flow-injection (FI) procedure was developed for the direct determination of water in organic solvents by using the O-H stretch absorbance band of water in the near-infrared (NIR) region. Dichloromethane was employed as a test solvent to study the influence of the flow parameters (carrier flow and sample injection volume) and time interval on the sensitivity and repeatability of the FI-NIR measurements. The developed procedure permits the determination of water in dichloromethane and isobutyl methyl ketone samples with limits of detection of 0.01 and 0.005% (v/v), respectively. Real and spiked samples of solvents were analysed by FI-NIR and accurate results were found. The method …

Determination of Mercury in Milk by Cold Vapor Atomic Fluorescence: A Green Analytical Chemistry Laboratory Experiment

Green analytical chemistry principles were introduced to undergraduate students in a laboratory experiment focused on determining the mercury concentration in cow and goat milk. In addition to traditional goals, such as accuracy, precision, sensitivity, and limits of detection in method selection and development, attention was paid to the evaluation of green parameters of the analytical methods. Milk samples were evaluated by cold vapor atomic fluorescence spectrometry (CV-AFS) and the wastes were minimized by co-precipitation with Fe(III).

Nanomaterials and new biorecognition molecules based surface plasmon resonance biosensors for mycotoxin detection

Mycotoxins are highly toxic secondary metabolites, which may contaminate many types of food and feeds. These toxins have serious health risks for both human and animals. One of the effective ways to prevent food contamination and protect people against mycotoxins is based on timely detection. Several methods like enzyme-linked immunosorbent assay and affinity chromatography are commercially available for this purpose. Nevertheless, sensitive, fast, simple, low-cost, and portable devices are absolutely required for a fast point-of care information and making decisions. Application of biosensors appears to be a possible technique to meet this need for mycotoxins analyze. The present study has…

Recent trends in rapid detection of influenza infections by bio and nanobiosensor

Abstract A literature update has been made about the progress and improvements in the use of biosensors for sensitive, rapid and specific detection of influenza virus. Background information about influenza virus and its structure together with a general discussion about the characteristics and significant aspects of different types of biosensors were used as a frame to put inside the main recent developments on the use of nanobiosensors for the detection of influenza virus. Working criteria of biosensors and their applications in different species of influenza virus diagnosis have been the primary concern of this review, which critically discusses the main advantages and limitations of stu…

ICP-MS multielement determination in fly ash after microwave-assisted digestion of samples.

A microwave assisted digestion procedure has been developed for dissolution of fly ash samples prior to the inductively coupled plasma-mass spectrometric determination of their elemental composition. The developed methodology was validated by carrying out the analysis of two high-silicate containing reference materials (CRM 134R sewage amended soil and NIES JR 1 rock) and by means of the comparison between results found by microwave-assisted digestion and ICP-MS of fly ash samples with those found by neutron activation analysis (NAA) for Sb, Cs, Cr, Co, Fe, U and Zn determination. The method developed can be recommended for routine multielement analysis of fly ash.

Recent advances in nanostructures and nanocrystals as signal-amplification elements in electrochemical cytosensing

Abstract Considering the vital role of cells in life science and human health, cytosensors have become a hot research topic. Electrochemical cytosensors attract much attention. In this review, we discuss some recent efforts to construct novel and improved electrochemical cytosensors based on graphene, carbon nanotubes, some metal-nanoparticle composites, quantum dots, nanofibers and nanowires. In addition, we summarize examples of nanostructure applications in electrochemical cytosensing reported in the literature from 2009 to date, with their advantages and limitations, and stress their potential for future development. Also, we focus on the current surface-modification strategies with som…

Noninvasive double confirmation of cocaine abuse.

A double confirmation procedure, based on the combined application of Ion Mobility Spectrometry (IMS) and Infrared Spectroscopy (IR), has been developed for the noninvasive unambiguous identification of cocaine consume. The use of nasal mucus as a biological specimen for cocaine abuse confirmation has been proposed as an alternative to the use of blood and urine due to its noninvasive character and the presence of the parent compound instead of its metabolites. Sampling conditions, interferences caused by cutting agents and other substances, and limits of identification (LOI) and confirmation (LOC) have been deeply evaluated. The procedure combines the high sensitivity of the IMS to identif…

Liquid–liquid equilibria in the system H3PO4–KCl–H2O–tri-n-butyl phosphate: experiments and modelling

Abstract The liquid–liquid equilibria of the system H3PO4–KCl–H2O–TBP was studied experimentally in the concentration range 0–6 mol/kg. The obtained data were modelled using the Pitzer equation for the aqueous phase and the Sergievskii–Dannus relationship for the organic phase. A fairly good agreement was observed between the model and the experimental data.

Estuarine sediment quality assessment by Fourier-transform infrared spectroscopy

Partial least squares Fourier-transform infrared (PLS-FTIR) models were developed for the quality assessment of estuarine sediments through the evaluation of several physico-chemical parameters. Models were based on the chemometric treatment of attenuated total reflection (ATR) spectra directly obtained from samples previously lyophilized and sieved through a lower than 63 μm grid. Spectra were scanned from 3997 to 523 cm-1, averaging 36 scans per spectrum with a nominal resolution of 8 cm-1. Models were built using reference data obtained for sediment samples collected from Ria de Arousa estuary. Hierarchical cluster classification of sediment ATR spectra was employed for the establishment…

Characterization of ethylene oxide/tert-octylphenol condensates by ultraviolet and infrared spectrometry

Abstract The average degree of condensation of ethylene oxide/tert-octylphenol condensate surfactants can be estimated rapidly by u.v. and i.r. spectrometry. The u.v. method is based on evaluating the specific absorptivity, a , at 275 nm in aqueous ethanol (60:40 v/v), and inserting this value in equations obtained from previously characterized samples, relating a to the average properties to be determined. Infrared spectrometry is applied similarly; the average properties to be determined are related to the ratio between the band heights at 960 and 840 cm −1 . The relative standard deviations ( n = 10) obtained for a sample of Triton X-100 were 2% by u.v. spectrometry, and 3% by i.r. spect…

On-line bi-directional electrostacking for As speciation/preconcentration using electrothermal atomic absorption spectrometry.

A method using bi-directional electrostacking (BDES) in a flow system is presented for As preconcentration and speciation analysis. Some parameters such as electrostacking time and applied voltage, support buffers and their concentrations were investigated. Boric acid plus sodium hydroxide at 0.1mol/l concentration was selected as support buffer to improve the pre-concentration factor (PF) for As(V). An analytical range from 2.0 to 50.0mugl(-1), and 0.35mugl(-1) as limit of detection, when applied 750V for 20min, were achieved. Under these conditions, a pre-concentration factor of 4.8 was obtained. The proposed method was applied to determine As(V) in mineral water and natural water samples…

Microwave-assisted vapour-generation Fourier transform infrared spectrometric determination of carbonate in waters

Abstract A microwave-assisted vapour-generation Fourier transform infrared spectrometric procedure is proposed for the determination of total carbonate in waters. The method is based on the simultaneous injection of 100 μl of sample and 300 μl of 0.1 M nitric acid in a two-channel manifold with a merging zone; a coil located inside a microwave oven encourages the removal of CO 2 . The carbon dioxide is separated from the distilled water employed as carrier by means of gas–liquid separator and is introduced by a nitrogen carrier flow inside a long-path infrared absorption gas cell, from which the corresponding flow analysis recording is registered as a function of time in the wavenumber rang…

Anti-bacterial activity of graphene oxide as a new weapon nanomaterial to combat multidrug-resistance bacteria.

Antibiotic resistance in microbial pathogens has become a serious health problem in the world. The increasing spread of hospital acquired infections especially in immunocompromised and cancer patients caused by multidrug-resistant (MDR) microbial pathogens is restricting the choices for impressive antibiotic therapy. So many efforts have been made to develop new compounds with antimicrobial activity. In recent years, nanoparticles, particularly graphene oxide (GO) nanoparticles have found many applications in various fields, including antibacterial action, pathogens bio detection, cancer therapy, and drug and gene delivery. The use of graphene oxide as an antibacterial agent for the treatme…

Application of the slurry technique to biological materials: a survey of literature

The literature on the application of the slurry technique to biological materials is reviewed. It is obvious from the various applications that the most frequently employed atomization method for slurry analysis in biological materials is electrothermal atomization using either graphite tube or platform atomizers. The slurry technique is particularly useful when certified reference materials are not available and when the standard addition method is to be avoided. The literature survey revealed that this technique compares favourably with other methods for the determination of trace metals in biological materials.

Microwave-assisted extraction of pyrethroid insecticides from semi permeable membrane devices (SPMDs) used to indoor air monitoring

Abstract A rapid and environmentally friendly methodology was developed for the extraction of pyrethroid insecticides from semi permeable membrane devices (SPMDs), in which they were preconcentrated in gas phase. The method was based on gas chromatography mass–mass spectrometry determination after a microwave-assisted extraction, in front of the widely employed dialysis method. SPMDs were extracted twice with 30 mL hexane:acetone, irradiated with 250 W power output, until 90 °C in 10 min, this temperature being held for another 10 min. Clean-up of the extracts was performed by acetonitrile–hexane partitioning and solid-phase extraction (SPE) with a combined cartridge of 2 g basic-alumina, d…

Multi-commutation in spectrometry

We review recent developments in manifold components and the introduction of light-emitting-diode technology in spectroscopic detection in order to evaluate the tremendous possibilities offered by multi-commutation for in-field and in-situ measurements, based on the use of multi-pumping and low-voltage, portable batteries, which make possible a dramatic reduction in size, weight and power requirements of spectrometric devices.

Deep eutectic solvents vs ionic liquids: Similarities and differences

Abstract Deep eutectic solvents (DES) were introduced as an alternative to ionic liquids (IL) to overcome the drawbacks of IL solvents. However, some authors consider them to be a subclass of ILs. In contrast, other authors emphasize that these are by their nature independent, different groups of substances. Thus, the question arises: Which solvent group should DESs belong to? Maybe a new class should be added to the existing ones. The aim of this work is to attract the attention of researchers using DES in their studies to the need for a proper use of terms.

Determination of ultratrace bismuth in milk samples by atomic fluorescence spectrometry.

Abstract A sensitive procedure was developed for determination of bismuth (Bi) in milk samples by hydride generation atomic fluorescence spectrometry (HG–AFS) after microwave-assisted sample digestion with HNO3 and H2O2. The method provides a sensitivity of 1832 fluorescence units (ng/mL) with a detection limit of 0.01 ng/mL, which corresponds to 20 pg absolute limit of detection, equivalent to 0.50 ng/g in the original sample. Application of the methodology to cow milk samples from the Spanish market showed the presence of Bi at a concentration of 11.8–28.8 ng/g, which compared well with data obtained after dry ashing of samples and with data obtained by inductively coupled plasma–mass spe…

Mesoporous silica-based materials for use in electrochemical enzyme nanobiosensors

Abstract Biology and medicine have seen great advancements in the development of enzyme nanobiosensors capable of characterizing and quantifying biomolecules. We provide an overview of mesoporous silica (MPS)-based enzyme nanobiosensors developed for biological and medical applications, and we describe significant advances in these technologies. We review progress in constructing high-performance electrochemical enzyme biosensors. We also discuss: • MCM-41 and SBA-15-modified and MPS composite electrodes for enzyme biosensing; • incorporation of biorecognition elements into MPS material electrodes for enzyme biosensing; and, • MCM-41 and SBA-15-supported electrocatalytic MPS-based electroch…

Multicommutation hydride generation atomic fluorescence determination of inorganic tellurium species in milk

Abstract A multicommutated flow system has been developed for hydride generation, atomic fluorescence (HG-AFS) determination of tellurate (Te VI ) and tellurite (Te IV ) in milk samples. After a batch leaching of Te by sonication at room temperature for 10 min with aqua regia, sample slurries in acidic medium were merged with sodium borohydride and HCl to obtain data on Te IV . Another portion of the acidic slurry was mixed with KBr and passed through a reaction coil introduced inside a microwave oven to reduce quantitatively Te VI to Te IV which was analyzed by HG-AFS. The detection limit was 0.57 ng g −1 in the original samples. The linear range obtained was till 4 ng ml −1 and the averag…

Determination of the mineral composition of foods by infrared spectroscopy: a review of a green alternative.

The determination of mineral composition of foods involves, in most cases, the use of long and tedious sample preparation, which consumes acids and reagents and sometimes requires the use of expensive instrumentation. This is the main reason for the search for direct analytical procedures, based on the use of infrared sample spectra and chemometrics, to model the signals in order to determine the presence of essential and trace toxic elements in foods. The state-of-the-art of the research in this field has been established in the present review article from the critical evaluation of articles available in the literature. Chemometric methods employed and their validation, together with a dis…

Monitoring of the smoking process by multicommutation Fourier Transform Infrared spectroscopy

Abstract Nicotine was selected as the target molecule for monitoring of the smoking process by multicommutation Fourier Transform Infrared spectroscopy (FTIR). The method involved the use of CHCl3 for on-line extraction of nicotine from tobacco, cigarette filters and tobacco ash from NH4OH alkalinized samples, and absorbance measurement of the characteristic band at 1316 cm−1 in the stopped-flow mode, by obtaining the peak area in the range between 1334 and 1300 cm−1. Under the best operational conditions, the procedure developed provided a detection limit of 0.05 mg mL−1 nicotine, corresponding to 0.5 mg g−1 in the solid sample, a relative standard deviation less than 2.5%, and a sampling …

Ensuring food safety using aptamer based assays: Electroanalytical approach

Aptamers, are being increasingly employed as favorable receptors for constructing highly sensitive biosensors, for their remarkable affinities towards certain targets including a wide scope of biological or chemical substances, and their superiority over other biologic receptors. The selectivity and affinity of the aptamers have been integrated with the wise design of the assay, applying suitable modifications, such as nanomaterials on the electrode surface, employing oligonucleotide-specific amplification strategies or, their combinations. After successful performance of the electrochemical aptasensors for biomedical applications, the food sector with its direct implication for human healt…

FT–Raman spectrometry determination of Malathion in pesticide formulations

Abstract A fast and environmentally friendly method has been developed for Fourier transform–Raman (FT–Raman) spectrometry determination of Malathion in pesticide emulsifiable concentrate formulations. The method is based on the measurement of intensity peak height values at 1737 cm −1 Raman shift corrected using a baseline defined at 1900 cm −1 . Samples were diluted with CHCl 3 and the FT–Raman spectra collected in back-scattering mode over 3.3 min at a nominal resolution of 4 cm −1 accumulating 50 scans per spectra and using a laser power of 1250 mW. The developed procedure provided a limit of detection of 1.8% w/w in the original sample. Results found by FT–Raman spectrometry were stati…

Fourier transform infrared determination of imidacloprid in pesticide formulations

A simple method has been developed for Fourier Transform Infrared (FTIR) determination of Imidacloprid in pesticide formulations. Samples were diluted with CHCl3 and the FTIR spectra of samples and standards were obtained at a nominal resolution of 4 cm-1 from 4000 to 900 cm-1 accumulating 25 scans. Imidacloprid determination was based on the measure of either peak area from 1577 to 1567 cm-1 or peak height at 1572 cm-1, both corrected using a horizontal baseline defined at 1900 cm-1. The limits of detection achieved, of the order of 9 µg g-1, were appropriate for the determination of Imidacloprid in commercially available formulations. FTIR results were statistically comparable to those fo…

Determination of mercury in rice by cold vapor atomic fluorescence spectrometry after microwave-assisted digestion.

Abstract A cold vapor atomic fluorescence spectrometry method (CV-AFS) has been developed for the determination of Hg in rice samples at a few ng g−1 concentration level. The method is based on the previous digestion of samples in a microwave oven with HNO3 and H2O2 followed by dilution with water containing KBr/KBrO3 and hydroxylamine and reduction with SnCl2 in HCl using external calibration. The matrix interferences and the effect of nitrogen oxide vapors have been evaluated and the method validated using a certified reference material. The limit of detection of the method was 0.9 ng g−1 with a recovery percentage of 95 ± 4% at an added concentration of 5 ng g−1. The concentration level …

Evaluation of the Soil Contamination of Tangier (Morocco) by the Determination of BTEX, PCBs, and PAHs

Benzene, toluene, ethylbenzene, and xylenes (BTEX), twelve polycyclic aromatic hydrocarbons (PAHs) and seven polychlorinated biphenyls (PCBs), were selected as pollutants to evaluate the contamination of soils in the urban and industrial areas of Tangier (Morocco). PAHs and PCBs were determined by gas chromatography-mass spectrometry (GC-MS) after a microwave-assisted extraction (MAE) and gel permeation chromatography (GPC) clean-up. BTEX were directly determined by head-space GC-MS. Results obtained in this study show the presence of high levels of BTEX and PAHs in the soil near the urban waste deposit. However, the analysis of pollutants in the other sampling sites provided comprehensive …

Vibrational spectroscopy provides a green tool for multi-component analysis

Abstract Based on the literature published in the past decade, we focus on the possibilities offered by vibrational-spectroscopy-based techniques to make multi-component analysis of samples independently of their physical state. We discuss the main chemometric tools proposed for developing calibration models and solving problems derived from spectroscopic non-idealities (e.g., highly overlapped spectral bands or the presence of spectral non-linearity), and the benefits provided by vibrational-spectroscopy-based multi-component analysis in industry. Our main objective is to show that vibrational spectroscopy provides fast analytical methods that enable non-destructive analysis and permits, i…

Sodium metabisulfite as a cytotoxic food additive induces apoptosis in HFFF2 cells

Sodium metabisulfite (SMB), an antioxidant agent, is extensively used as a preservative in food industry. The current study was aimed to clarify its potential toxic effects on human fetal foreskin fibroblasts (HFFF2) cells, in vitro. Subsequently, MTT results illustrated that exposure to SMB significantly (p  0.0001) decreased HFFF2 cell viability in a dose-dependent manner, and the concentration of 25 μM reduced cell survival rates to 50% as the half-maximal inhibitory concentration of SMB. It was further shown that SMB exerted this cytotoxic effect on HFFF2 cells through apoptosis induction. qRT-PCR and western blotting results showed that treatment of HFFF2 cells with this food additive …

Vibrational Spectroscopy

The molecular information provided by the vibrational spectra obtained by both absorption in the near-infrared and middle-infrared range and Raman dispersion has been critically evaluated to obtain specific information for the authentication of protected designation of origin foods and other food geographical indications. The literature in this field has been updated and the capability of the vibrational spectra to provide discrimination between foods produced in different areas and by using different processes are also discussed.