Search results for "Analyte"
showing 10 items of 303 documents
Selectivity tuning in pressurized-flow electrochromatography
1996
Abstract Pressurized-flow electrochromatography (PEC) is a developing separation technique in which both a pressure gradient and an electric field are applied across a packed capillary. In this work we present new results illustrating the principles and the potential of PEC. Home-made capillary columns with silica-based reversed phase packings were operated under PEC conditions separating low molecular weight analytes. Compared to the purely pressure-driven system enhanced selectivity for the charged analytes was observed. It is shown that the retention time of a retained cationic analyte in PEC can be calculated using the chromatographic capacity factor and the electrophoretic mobility of …
Flow-Injection Solid Phase Partial Least-Squares Spectrophotometric Simultaneous Determination of Iron, Nickel and Zinc
2002
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…
Implementation of multicommutation principle with flow-through multioptosensors
2005
Abstract For the first time, the combination of multicommutation concept with flow-through multioptosensors is exploited and a biparameter multicommutated UV sensor is developed. A very easy-operated and automated sensing device is proposed here and demonstrated to be useful in the routine analysis by applying it to the determination of two widely used pharmaceuticals chosen as model analytes: salicylamide and caffeine. The particulated solid phase used performs two functions: (a) states selectivity conditions by itself in the flow cell and (b) provides appropriate separation of the analytes in the on-line precolumn, thus making possible the sequential arrival of the analytes to the detecti…
Evaluation of the interelemental effect in X-ray fluorescence analysis by the total addition method
1992
An algorithm for quantifying interelemental effects in X-ray fluorescence techniques is developed. By applying an addition process, the ratio between the mass absorption coefficients of the analyte and the unknown sample (μi*/μs*) is calculated to correct the fluorescence intensity of the element to be determined and linearize the I-c calibration plot. This coefficient can be calculated graphically and numerically. The method is applied to the determination of tin in lead alloys with good results over wide concentration ranges.
Target Analysis and Retrospective Screening of Multiple Mycotoxins in Pet Food Using UHPLC-Q-Orbitrap HRMS
2019
A comprehensive strategy combining a quantitative method for 28 mycotoxins and a post-target screening for other 245 fungal and bacterial metabolites in dry pet food samples were developed using an acetonitrile-based extraction and an ultrahigh-performance liquid chromatography coupled to high-resolution mass spectrometry (UHPLC-Q-Orbitrap HRMS) method. The proposed method showed satisfactory validation results according to Commission Decision 2002/657/EC. Average recoveries from 72 to 108% were obtained for all studied mycotoxins, and the intra-/inter-day precision were below 9 and 14%, respectively. Results showed mycotoxin contamination in 99% of pet food samples (n = 89) at concentratio…
DNA quantification approach by GE-ICP-SFMS and complementary total phosphorus determination by ICP-SFMS
2006
Quantification of DNA is still a great challenge for scientists in many fields. Here, we present the on-line coupling of gel electrophoresis (GE) and inductively coupled plasma-sector field mass spectrometry (ICP-SFMS) for quantitative purposes. GE conditions are chosen for optimised separations depending on the target analyte composition in terms of DNA chain length. In particular, agarose concentrations are varied in the range 0.6–2.2%, which corresponds to a separation range of DNA from 100 base pairs (bp) to genomic DNA (approximately 3 Mbp). Separated DNA compounds are directly transported at a flow rate of 100 μL min−1 to a Micromist nebuliser which is followed by ICP-SFMS with 31P de…
Quantitative colorimetric-imaging analysis of nickel in iron meteorites.
2011
A quantitative analytical imaging approach for determining the nickel content of metallic meteorites is proposed. The approach uses a digital image of a series of standard solutions of the nickel-dimethylglyoxime coloured chelate and a meteorite sample solution subjected to the same treatment as the nickel standards for quantitation. The image is processed with suitable software to assign a colour-dependent numerical value (analytical signal) to each standard. Such a value is directly proportional to the analyte concentration, which facilitates construction of a calibration graph where the value for the unknown sample can be interpolated to calculate the nickel content of the meteorite. The…
Hapten Synthesis and Polyclonal Antibody-Based Immunoassay Development for the Analysis of Forchlorfenuron in Kiwifruit
2010
High-affinity polyclonal antibodies directed against the synthetic cytokinin forchlorfenuron (CPPU) were produced from three immunizing haptens with equivalent spacer arms located at different positions. A competitive immunoassay was developed with a limit of detection in buffer of 12.42 +/- 3.06 ng/L. In addition, the ability of the produced antibodies to recognize a set of synthetic CPPU analogues was studied. It was evidenced that the linker position had a strong impact on the specificity of the generated polyclonals, which were more sensitive to changes at moieties of the target analyte located furthest from the derivatization site of the immunogen. Finally, matrix effects of gold and g…
A passive solid sensor for in-situ colorimetric estimation of the presence of ketamine in illicit drug samples
2017
Abstract A colorimetric sensor has been developed for the presumptive detection of ketamine in illicit drug samples. The sensor has been prepared by immobilized the reagent Co(SCN) 2 into polydimethylsiloxane (PDMS). When exposed to solutions of ketamine at a basic pH, the sensor color changes from brown to blue-purple due to the diffusion of the analyte molecules to the polymeric matrix and subsequent interaction with the reagent particles. The sensor enables the visual identification of amounts of drug as low as 30 μg in a few minutes. Quantification of ketamine is also possible through the measurement of the absorbance in diffuse reflectance mode. Under the proposed conditions, linear re…
In Situ Ammonium Profiling Using Solid-Contact Ion-Selective Electrodes in Eutrophic Lakes
2015
A promising profiling setup for in situ measurements in lakes with potentiometric solid-contact ion-selective electrodes (SC-ISEs) and a data processing method for sensor calibration and drift correction are presented. The profiling setup consists of a logging system, which is equipped with a syringe sampler and sensors for the measurement of standard parameters including temperature, conductivity, oxygen and photosynthetically active radiation (PAR). The setup was expanded with SC-ISEs in galvanically separated amplifiers. The potential for high-resolution profiling is investigated by deploying the setup in the eutrophic Lake Rotsee (Lucerne, Switzerland), using two different designs of am…