Determination of testosterone:epitestosterone ratio after pentafluorophenyldimethylsilyl-trimethylsilyl derivatisation using gas chromatography-mass spectrometry in equine urine.
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%.
Choi
M H
MH
Doping Control Center, Korea Institute of Science and Technology, Cheongryang, Seoul, Korea.
Kim
J Y
JY
Chung
B C
BC
D000818:Animals; D004845:Epitestosterone / Q000652:urine; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods; D006736:Horses / Q000652:urine*; D008297:Male; D013739:Testosterone / Q000652:urine*
D013739:Testosterone; D004845:Epitestosterone