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Liquid chromatography electrospray ionization tandem mass spectrometry for the detection of mesocarb abuse in horse doping
Author(s) -
Appolonova Svetlana A.,
Baranov Pavel A.,
Mesonzhnik Natalia V.,
Brazhnikova Daria O.,
Rodchenkov Grigory M.
Publication year - 2011
Publication title -
drug testing and analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.065
H-Index - 54
eISSN - 1942-7611
pISSN - 1942-7603
DOI - 10.1002/dta.345
Subject(s) - chromatography , chemistry , electrospray ionization , mass spectrometry , tandem mass spectrometry , urine , metabolite , hydroxylation , liquid chromatography–mass spectrometry , enzyme , biochemistry
A method is described for the determination of mesocarb abuse in equestrian sport by combining gradient liquid chromatography and electrospray ionization tandem mass spectrometry. Mesocarb was administrated orally to two horses at a dose of 50 µg/kg. Urine samples were collected up to 120 h post administration. Hydrolyzed and conjugated urine fractions were handled using liquid‐liquid extraction (LLE). The identity of the parent drug and metabolites was confirmed using liquid chromatography combined with tandem mass spectrometry (MS/MS). Mesocarb and seven metabolites were detected in horse urine. Mono‐ and two di‐hydroxylated metabolites were the main metabolites observed in horse urine samples. Based on the differences in MS/MS spectra it was supposed that these metabolites were been formed by the hydroxylation of the phenylisopropyl moiety of mesocarb whilst the main process of hydroxylation of mesocarb in human occurred in the phenylcarbamoyl moiety. The main metabolites were almost completely glucuroconjugated. Minor metabolites such as p‐hydroxymesocarb and three di‐hydroxylated metabolites together with parent mesocarb were also presented in the free urine fraction. This study has shown that two mono‐ and two di‐hydroxylated metabolites are useful for controlling the abuse of mesocarb in horses. Copyright © 2011 John Wiley & Sons, Ltd.