URINARY TESTOSTERONE (T) TO EPITESTOSTERONE (E) RATIOS BY GC MS .1. INITIAL COMPARISON OF UNCORRECTED T/E IN 6 INTERNATIONAL LABORATORIES/

Six laboratories in six countries collaborated to investigate the anal ytical method for estimating the testosterone to epitestosterone ratio (T/E) in urine by gas chromatography/mass spectrometry in the context of detecting the application of T as a doping agent in sport. The pro tocol specified many but not all details of reagents and instrument co nditions. The design included the distribution and analysis of four ur ines with different T/E values, three replicates per value, and one st andard. The ranges of mean T/E values for the four urines estimated by peak area (PA) were 0.32-0.42, 0.72-0.94, 0.91-1.14 and 3.19-5.48. Th e analyses of variance for these data and for the peak height (PH) dat a were significant for the laboratory factor (p < 0.0001). In addition there was a significant interaction between the urine factor and the laboratory factor which indicates the complexity of the analysis. T/E calculated using PA was not significantly different from that using PH . For within-laboratory precision all values for PH and PA were < 8.3% , and for between-laboratory precision all values were < 11.7% except for one (20.1%). The data represent a baseline for future experiments designed to elucidate the sources of within-and between-laboratory var iance, and to harmonize estimates of T/E.