title: Determination of dexamethasone in urine by gas chromatography with negative chemical ionization mass spectrometry.
abstract: Dexamethasone, as some other synthetic corticosteroids, is licensed for therapy in veterinary practice, but its misuse as a growth promotor, often in combination with beta-agonists, is forbidden. In this report an analytical method is described for the detection and confirmation of very low concentrations of dexamethasone in urine. The influence of enzymatic hydrolysis time of samples with glucuronidase was studied. The proposed method consisted of the enzymatic hydrolysis of urine samples, which were then extracted and concentrated using solid-phase cartridges with mixed reversed-phase materials (OASIS). No further clean-up step was found to be necessary. Eluates were derivatized following a previously described method [Analyst 119 (1994) 2557]. Detection, identification and quantification of residues of this compound was carried out by gas chromatography with mass spectrometry in the negative chemical ionization mode. The proposed procedure permits the determination of dexamethasone in urine at levels as low as 0.2 ng ml(-1)
authors.affiliation: Centro Nacional de Alimentación, Agencia Española de Seguridad Alimentaria, Carretera Majadahonda-Pozuelo Km. 2, Spain.
authors.forename: Olga
authors.initials: O
authors.lastname: Huetos Hidalgo
authors.forename: Manuel
authors.initials: M
authors.lastname: Jiménez López
authors.forename: Elisa
authors.initials: E
authors.lastname: Ajenjo Carazo
authors.forename: Manuel
authors.initials: M
authors.lastname: San Andrés Larrea
authors.forename: Thea B A
authors.initials: TB
authors.lastname: Reuvers
mesh_terms: D000818:Animals; D002138:Calibration; D003907:Dexamethasone / Q000652:urine*; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D006801:Humans; D012015:Reference Standards; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D003907:Dexamethasone