GAS-CHROMATOGRAPHY COMBUSTION ISOTOPE RATIO MASS-SPECTROMETRY ANALYSIS OF URINARY STEROIDS TO DETECT MISUSE OF TESTOSTERONE IN SPORT

We propose a new confirmatory method for testosterone doping in sport. The present method in use, based on measuring the testosterone/epites tosterone (T/E) ratio in urine, may miss suspicious cases, or lead to reporting cases in which the high ratio is natural. Synthetic testoste rone has a C-13 abundance different from that of endogenous human test osterone. The connection of a gas chromatograph to an isotope-ratio ma ss spectrometer via a combustion interface allows the measurement of t he corresponding characteristic value (delta parts per thousand) for t estosterone, its precursors, and its metabolites. To detect exogenous administration of testosterone, 30-40 mL of urine is sufficient.