title: Determination of testosterone:epitestosterone ratio after pentafluorophenyldimethylsilyl-trimethylsilyl derivatisation using gas chromatography-mass spectrometry in equine urine.
abstract: A highly specific method is described for measuring the testosterone:epitestosterone ratio in equine urine by gas chromatography-mass spectrometry (GC-MS) with stable isotope internal standards. The procedure was based on Serdolit Pad-1 resin extraction, enzymatic hydrolysis, and chemical derivatisation prior to instrumental analysis. The mixed derivatives, 3-trimethylsilyl-17-pentafluorophenyldimethylsilyl ether (3-TMS-17-flophemesyl) testosterone and epitestosterone, were found to have excellent analytical properties. The specificity of the derivatisation method exploits a unique feature of steroids: the selective exchange of the alcoholic flophemesyl ether for the trimethylsilyl ether. The sensitivity and specificity of the mixed 3-TMS-17-flophemesyl derivatives allow adequate determinations of testosterone and epitestosterone, even in urine from mares, in 5 ml samples. The repeatability of testosterone and epitestosterone was 6.2 and 5.7%, respectively, and their reproducibility was in the range of 6.4-8.7%.
authors.affiliation: Doping Control Center, Korea Institute of Science and Technology, Cheongryang, Seoul, Korea.
authors.forename: M H
authors.initials: MH
authors.lastname: Choi
authors.forename: J Y
authors.initials: JY
authors.lastname: Kim
authors.forename: B C
authors.initials: BC
authors.lastname: Chung
mesh_terms: D000818:Animals; D004845:Epitestosterone / Q000652:urine; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods; D006736:Horses / Q000652:urine*; D008297:Male; D013739:Testosterone / Q000652:urine*
chemical_list: D013739:Testosterone; D004845:Epitestosterone