[Trimethylsilylation of testosterone, epi-testosterone and determination of their ratio in urine by GC-MS].

The trimethylsilylation of testosterone and epitestosterone was discussed in detail in this report. Both derivative conditions under which testosterone and epi-testosterone were prepared into TMS-derivatives in the presence of mercaptoethanol as an antioxidizing agent and method for the analysis of the ratio of testosterone to epi-testosterone in urine, based on GC-MS, had been established. The conditions of detection were: carrier gas was helium, derivatives were separated with SE-54 fused silica capillary column, using temperature program and detected by using multiple ion detection mode in which the ion of m/z 432 was the monitoring ion. The method is rapid, sensitive and specific. For the ratio of testosterone to epi-testosterone (testosterone: 20 ng/microliters), there is a linearity between ratio 1:1 and 10:1 (r = 0.998), the limit of detection for testosterone and epi-testosterone is 1 ng, and the minimum concentration of detection in urine is 8 ng/ml.