Determination of urinary steroid sulfate metabolites using ion paired extraction

The need for laboratories accredited by the World Anti-Doping Agency (WADA) to develop methods of analysis for steroids excreted primarily as their sulfate conjugates has faced significant analytical challenges. One of the issues relates to the extraction of these metabolites from urine in a relatively pure state. The use of (−)-N,N-dimethylephedrinium bromide as an ion pairing reagent was optimised to produce a method that is selective for the extraction of steroid sulfates prior to GC-MS or LC-MS analysis, with minimal contributions from the urine matrix. The recovery of androsterone from its sulfate conjugate was determined to be 67% with a relative quantitative uncertainty of ±14% (k = 2).