Search results for "Detection limit"
showing 10 items of 810 documents
Green methodology for quality control of elemental content of infant milk powder
2019
Abstract A green methodology for the direct determination of elemental content in infant milk powder samples from 0 to 3 years was developed. A portable energy dispersive X-ray fluorescence (ED-XRF) tool has been used as a direct method for the quantification of five essential elements (Ca, K, Fe, Cu and Zn). For analysis pellets from 0.8 g of each sample weight were made and analyzed. Due to the high dependence of the ED-XRF signal with the sample matrix, external calibrations using cocoa powder diluted with glucose were performed. Infant milk samples were diluted with lactose and the signals were interpolated in the external calibrations. Concentrations obtained by ED-XRF were compared wi…
Colorimetic biosensing dispositive based on reagentless hybrid biocomposite: Application to hydrogen peroxide determination
2016
Abstract An efficient approach to enhance the performance of colorimetric biosensors has been developed. The biosensor is based on the co-immobilization of the reagent 3,3′,5,5′-teramethylbencidine (TMB) and the enzyme horseradish peroxidase (HRP) in a PDMS-TEOS-SiO2NPs support. The HRP, in presence of H2O2, catalyzes the oxidation of TMB, producing a blue color. The generated biosensor, doped with the substrate (TMB) and the enzyme (HRP) (entrapped or adsorbed), has been used to determine H2O2 in real samples. Firstly, the immobilization of TMB and HRP in the composite has been studied in order to find the best suitable configuration. The kinetic parameters Vmax (maximum reaction rate) and…
Comprehensive analysis of photoinitiators and primary aromatic amines in food contact materials using liquid chromatography High-Resolution Mass Spec…
2018
Abstract A comprehensive strategy for the analysis of UV-ink photoinitiators and primary aromatic amines (PAAS) in food-packaging materials such as, juice tetrabricks, pouches and bags has been developed using liquid chromatography coupled to Orbitrap High-Resolution Mass Spectrometry (LC-Orbitrap-HRMS). The methodology includes both quantitative target analysis and post-run target screening analysis. The quantitative method was validated after a previous optimisation of the single-stage Orbitrap fragmentation through the Higher-Energy Collisional Dissociation (HCD) Cell. Overall, the quantitative method presented recoveries ranging from 78% to 119%, with a precision (RSD) lower than 20%, f…
Cholesterol Content in Human Milk during Lactation: A Comparative Study of Enzymatic and Chromatographic Methods.
2018
This study validates a gas chromatography (GC) method for determining the sterol profile of human milk (HM) and compares it with an enzymatic-spectrophotometric (E-S) method. Good linearity ( r > 0.97) and low limits of detection and quantification were obtained with the GC method (<1.8 and <6 μg/100 g of HM, respectively). Suitable intra- and interassay precisions (all <18%) and satisfactory recovery percentages (80-109%) were obtained for both methods. In addition, both methodologies were used to assess cholesterol evolution in HM during lactation, showing a 50% decrease at 6 months versus colostrum. The E-S method overestimated cholesterol content by <20% versus the GC method. The result…
Reliable determination of new lipid peroxidation compounds as potential early Alzheimer Disease biomarkers.
2018
Lipid peroxidation plays an important role in Alzheimer Disease, so corresponding metabolites found in urine samples could be potential biomarkers. The aim of this work is to develop a reliable ultra-performance liquid chromatography-tandem mass spectrometry analytical method to determine a new set of lipid peroxidation compounds in urine samples. Excellent sensitivity was achieved with limits of detection between 0.08 and 17 nmol L-1, which renders this method suitable to monitor analytes concentrations in real samples. The method's precision was satisfactory with coefficients of variation around 5-17% (infra-day) and 8-19% (inter-day). The accuracy of the method was assessed by analysis o…
Sterols in infant formulas: validation of a gas chromatographic method.
2017
AbstractSterols are components present in the fat fraction of infant formulas (IFs). Their characterization is therefore of interest, though there are no official reference methods for their analysis in these matrices.Aim: To validate a gas chromatographic method with flame ionization detection for the determination of animal (cholesterol and desmosterol) and plant sterols (brassicasterol, campesterol, stigmasterol, β-sitosterol and sitostanol) found in IFs.All correlation coefficients obtained for the calibration curves of sterols studied were >0.99. Limits of detection (<1 μg/100 mL) and quantification (<4 μg/100 mL) are suitable for sterols determination in IFs. The within-assay precisio…
First report on the presence of Alloxan in bleached flour by LC-MS/MS method
2017
Abstract In this work the presence of Alloxan in bread, pastry and cake bleached flour was investigate in order to verify possible risk for consumers related to the use of chemicals for flour bleaching. A selective UHPLC–MS/MS method has been developed and validated for the purpose. Alloxan is one of the possible minor side products of oxidation after chemical bleaching of wheat flours, when several chemical agents are used. One hundred and seventy-five flour samples were analyzed for Alloxan determination. The validation of the method was performed in accordance with the ISO/IEC/EN 17025 for linearity, detection limit, quantification limit, accuracy, precision and ruggedness determination.…
Assessment of ISO Method 15216 to Quantify Hepatitis E Virus in Bottled Water
2020
Hepatitis E virus (HEV) is one of the causative agents of water-borne human viral hepatitis and considered in Europe an emerging zoonotic pathogen. Analysis of bottled water through a standard method validated for HEV can contribute towards the risk management of this hazard. Putting some recent reports by the European Food Safety Authority in place, this study aimed to assess the performance of the concentration and extraction procedures described in ISO 15216-1:2017 for norovirus and hepatitis A virus on HEV detection. Following the ISO recommendation, the bottled water samples were spiked using serially diluted HEV fecal suspensions together with mengovirus as process control and concent…
Development of an Analytical Assay for Electrochemical Detection and Quantification of Protein-Bound 3-Nitrotyrosine in Biological Samples and Compar…
2020
Reactive oxygen and nitrogen species (RONS) cause oxidative damage, which is associated with endothelial dysfunction and cardiovascular disease, but may also contribute to redox signaling. Therefore, their precise detection is important for the evaluation of disease mechanisms. Here, we compared three different methods for the detection of 3-nitrotyrosine (3-NT), a marker of nitro-oxidative stress, in biological samples. Nitrated proteins were generated by incubation with peroxynitrite or 3-morpholino sydnonimine (Sin-1) and subjected to total hydrolysis using pronase, a mixture of different proteases. The 3-NT was then separated by high performance liquid chromatography (HPLC) and quantifi…
External Influences on Invertebrate Brain Histamine and Related Compounds via an Automated Derivatization Method for Capillary Electrophoresis.
2017
8 pages; International audience; Histamine has been shown to modulate visual system and photic behavior in arthropods. However, few methods are available for the direct quantification of histamine and its precursor and metabolites in arthropod brain. In this work, a method for the separation of histamine, its precursor histidine, and its metabolite N-methyl-histamine from brain extracts of a freshwater crustacean has been developed using capillary electrophoresis with laser-induced fluorescence detection. Molecules were tagged on their primary amine function with naphthalene-2,3-dicarboxaldehyde, but derivatized histamine and N-methyl-histamine exhibited poor stability in contrast to deriva…