Search results for "Spectroscopy"
showing 10 items of 10293 documents
Enhanced flow-injection–chemiluminometric determination of sulphonamides by on-line photochemical reaction
2003
Abstract The viability of the tandem photochemical reaction-chemiluminescence detection has been studied for an heterogeneous group of sulphonamides (sulphamethoxazole, sulphadiazine, sulphamerazine, sulphamethoxypyridazine, sulphacetamide, sulphadimidine, sulphanilamide, sulphathiazole and sulphaguanidine) using sulphamethoxazole (whose chemiluminescent behaviour has not been previously reported) as a test substance. The ‘on-line’ photochemical-reaction of sulphonamides provides an enhancing influence on the chemiluminometric response of the drugs during their oxidation by potassium permanganate in sulphuric acid medium (sulphamethoxazole, sulphacetamide, sulphadimidine and sulphanilamide …
A reliable and environmentally-friendly liquid-chromatographic method for multi-class determination of fat-soluble UV filters in cosmetic products.
2013
An environmentally-friendly analytical method for the simultaneous determination of 15 fat-soluble ultraviolet (UV) filters currently authorized by the European Union regulation on cosmetic products has been developed. The determination was performed by liquid chromatography with UV spectrophotometric detection. Different parameters, such as type of column, oven temperature, mobile phase composition and flow rate were studied. The best chromatographic separation was obtained under the following conditions: C18 column set at 60°C and gradient ethanol:water (containing 1% formic acid and 20mM of 2-hydroxypropyl-β-cyclodextrin) as mobile phase pumped at 1mL min(-1). 2-Hydroxypropyl-β-cyclodext…
Hydride generation atomic fluorescence spectrometric determination of ultratraces of selenium and tellurium in cow milk
2003
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.
Direct vapor generation Fourier transform infrared spectrometric determination of ethanol in blood
1996
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…
Mid- and near-infrared determination of metribuzin in agrochemicals
2008
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 …
Novel approach for the determination of azithromycin in pharmaceutical formulations by Fourier transform infrared spectroscopy in film-through transm…
2013
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…
Uptake and translocation monitoring of imidacloprid to chili and tomato plants by molecularly imprinting extraction - ion mobility spectrometry
2019
Abstract The degradation of imidacloprid in soil and its uptake and translocation to chili and tomato plants was evaluated, as a proof of concept, of the possibilities of the combination of molecularly imprinted polymers (MIPs) and ion mobility spectrometry (IMS) for a fast and sensitive bioprocesses monitoring tool. To do it, a method based on the selective extraction of imidacloprid from soil and plant materials was developed. In the selected conditions, the MIP-IMS procedure provided a recovery of imidacloprid in soil and plant samples from 102 to 114%, for spiked concentration levels from 0.2 to 2.0 μg g−1. Precision of the methodology, expressed as the relative standard deviation (RSD)…
Fourier transform infrared determination of imidacloprid in pesticide formulations
2004
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…
On-line speciation of mercury in fish by cold vapour atomic fluorescence through ultrasound-assisted extraction
2004
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…
Optimization of LC–MS/MS using triple quadrupole mass analyzer for the simultaneous analysis of carbosulfan and its main metabolites in oranges
2006
This paper describes an analytical method involving a simple solvent extraction for the simultaneous liquid chromatography coupled to quadrupole tandem mass spectrometry (LC-MS/MS) determination of carbosulfan, its most toxic metabolite--carbofuran--, and its other main metabolites--3-hydroxycarbofuran, 3-ketocarbofuran, 3-hydroxy-7-phenolcarbofuran, 3-keto-7-phenolcarbofuran, 7-phenolcarbofuran and dibutylamine--in oranges. Chromatography was performed on a Zorbax Bonus-RP (150 mm x 2.1 mm, 5 microm). The mobile phase was a ternary gradient water-methanol-acetonitrile with 1.0 mM ammonium acetate at flow rate of 0.2 ml min(-1). The LC separation and MS/MS optimization were studied to selec…