Analysis of steroids in human urine by on line liquid chromatography-gas chromatography-mass spectrometry using the Through Oven Transfer Adsorption Desorption interface and a fraction collector.

Anti-doping laboratories accredited by the WADA (World Anti-Doping Agency) must have available methods capable of detecting synthetic steroids at concentrations below 10ngmL−1 and, at the same time, be able to quantify endogenous steroids with accuracy. The unequivocal identification of the steroids must be carried out by GC–MS. In this manuscript we describe a new method by on-line coupled liquid chromatography–gas chromatography (LC–GC) using the Through Oven Transfer Adsorption Desorption (TOTAD) interface and mass spectrometer (MS) detector. By this means, all the analyte eluted in the LC stage are automatically transferred to the GC, avoiding the contamination associated with manipulation of the sample. A newly designed fraction collector is described for the first time. The collector permits the different fractions eluted in LC to be stored and sent individually to the GC by means of the TOTAD interface. The detection limits attained, measured in gas chromatography–mass spectrometry (GC–MS) in SCAN mode, vary between 0.5 and 3.4ngmL−1, and the method, once the sample is derivatized, is completely automatic.