21 research outputs found
Application of Gas Chromatography to Determination of Total Organic Fluorine after Defluorination of Perfluorooctanoic Acid as a Model Compound
Because of the global presence of anthropogenic perfluorinated organic compounds in the environment,
foods and living organisms, and their large structural variety, it can be helpful to develop a method
for determination of their total content at trace level in different matrices. In the developed method,
the defluorination was carried with sodium biphenyl, derivatization of released fluoride to triphenylfluorosilane
and determination by gas chromatography. Three detection methods were compared: flameionization
detection, electron capture detection and mass spectrometry. Among them the MS detection
was found to be the most favorable one in terms of the instrumental limit of detection (LOD) , whereas the
flame-ionization detection was considered to be the most favorable in terms of the method limit of detection
(MDL). For the initial sample volume of 1 L and performing the whole procedure of determination,
including preconcentration, the MDL value for perfluorooctanoic acid was evaluated as 0.043 ppb. (doi: 10.5562/cca1798
New Analytical Methods Developed for Determination of Perfluorinated Surfactants in Waters and Wastes
Perfluorinated organic compounds have been recognized in recent years as globally distributed
persistent organic pollutants of an entirely anthropogenic origin, but present already even in the most
remote places of the globe, including organisms of wild fauna. Numerous studies have also shown that
they are contained in human organisms all over the world. In this work a special attention is given to
perfluorinated carboxylic acids (PFCAs), widely used in various areas of modern life. New methods
developed for their determination using the HPLC with fluorescence detection and capillary electrophoretic
methods are discussed, as well as the new method for the determination of total organic fluorine
(TOF). (doi: 10.5562/cca1776
Measurement of melatonin in body fluids: Standards, protocols and procedures
Abstract: The circadian rhythm of melatonin in saliva or plasma, or of the melatonin metabolite 6‐ sulphatoxymelatonin in urine, is a defining feature of suprachiasmatic nucleus function, the endogenous oscillatory pacemaker. These measurements are useful to evaluate problems related to the onset or offset of sleep and for assessing phase delays or advances of rhythms in entrained individuals. Additionally, they have become an important tool for psychiatric diagnosis, its use being recommended for phase typing in patients suffering from sleep and mood disorders. Thus, the development of sensitive and selective methods for the precise detection of melatonin in tissues and fluids of animals emerges as necessary. Due to its low concentration and the co‐existence of many other endogenous compounds in blood, the determination of melatonin has been an analytical challenge. This review discusses current methodologies employed for detection and quantification of melatonin in biological fluids and tissues
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Abstract: A sensitive liquid chromatographic-single quadrupole mass spectrometric method was developed and validated for the determination of lapatinib in human plasma. Following a liquid-liquid extraction with methyl t-butyl ether, lapatinib and isotope labelled lapatinib, used as an internal standard (IS), were separated from the endogenous compounds on a Zorbax SB-C18 (150 ◊ 3 mm, 3.5 µm) column. An isocratic elution with the mobile phase consisting of formic buffer and the mixture of acetonitrile, methanol and formic acid was used. Mass spectrometry with positive electrospray ionization in a single ion monitoring mode was applied. The proposed method provides the satisfactory recovery of lapatinib from human plasma and a sensitivity comparable to numerous tandem mass spectrometric methods, with a lower limit of quantification of 5 ng/mL. The validated method may be applied to pharmacokinetic studies in humans following a single 250 mg oral dose