title: Urinary testosterone (T) to epitestosterone (E) ratios by GC/MS. I. Initial comparison of uncorrected T/E in six international laboratories.
abstract: Six laboratories in six countries collaborated to investigate the analytical 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 protocol specified many but not all details of reagents and instrument conditions. The design included the distribution and analysis of four urines with different T/E values, three replicates per value, and one standard. 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. The analyses of variance for these data and for the peak height (PH) data 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 variance, and to harmonize estimates of T/E.
authors.affiliation: Department of Molecular and Medical Pharmacology, University of California at Los Angeles, USA.
authors.forename: D H
authors.initials: DH
authors.lastname: Catlin
authors.forename: D A
authors.initials: DA
authors.lastname: Cowan
authors.forename: R
authors.initials: R
authors.lastname: de la Torre
authors.forename: M
authors.initials: M
authors.lastname: Donike
authors.forename: D
authors.initials: D
authors.lastname: Fraisse
authors.forename: H
authors.initials: H
authors.lastname: Oftebro
authors.forename: C K
authors.initials: CK
authors.lastname: Hatton
authors.forename: B
authors.initials: B
authors.lastname: Starcevic
authors.forename: M
authors.initials: M
authors.lastname: Becchi
authors.forename: X
authors.initials: X
authors.lastname: de la Torre
authors.forename: H
authors.initials: H
authors.lastname: Norli
authors.forename: H
authors.initials: H
authors.lastname: Geyer
authors.forename: C J
authors.initials: CJ
authors.lastname: Walker
mesh_terms: D000704:Analysis of Variance; D004300:Doping in Sports; D004845:Epitestosterone / Q000652:urine*; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D007202:Indicators and Reagents; D007753:Laboratories; D012015:Reference Standards; D015203:Reproducibility of Results; D013739:Testosterone / Q000652:urine*
chemical_list: D007202:Indicators and Reagents; D013739:Testosterone; D004845:Epitestosterone