C-13/C-12 isotope ratio MS analysis of testosterone, in chemicals and pharmaceutical preparations

The C-13/C-12 ratio can be used to detect testosterone misuse in sport beca use (semi)-synthetic testosterone is supposed to have a C-13 abundance diff erent from that of endogenous natural human testosterone. In this study, ga s chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) ana lysis for the measurement of the delta C-13% value of testosterone from est erified forms of 13 pharmaceutical preparations, six reagent grade chemical s and three bulk materials (raw materials used in pharmaceutical proaration s) obtained world-wide was investigated after applying a strong acidic solv olytic procedure. Mean delta C-13% values of non esterified (free) testoste rone from chemicals and bulk materials of several testosterone esters were in the range: -25.91/-32.82% while the value obtained for a (semi)-syntheti c, reagent gr adc, free testosterone was -27/.36%. The delta C-13% results obtained For testosterone from the pharmaceuticals investigated containing testosterone esters were quite homogeneous (mean and S.D. of delta C-13% va lues of free testosterone 27.43 +/- 0.76%), being the range between -26.18 and -30.04%. Values described above were clearly different From those repor ted by several authors for endogenous natural human testosterone and its ma in metabolites excreted into the urine in non-consumers of testosterone (de lta C-13% range: from -21.3 to -24.4%), while they were similar to those of urinary testosterone and metabolites from individuals treated with testost erone eaters and testosterone precursors. This finding justifies the fact t hat administration of these pharmaceutical formulation led to a statistical decrease of carbon isotope ratio of urinary testosterone and its main meta bolites in treated subjects. (C) 2001 Elsevier Science B.V. All rights rese rved.