A screening method for the detection of synthetic glucocorticosteroids in human urine by liquid chromatography-mass spectrometry based on class-characteristic fragmentation pathways

This paper describes a liquid chromatographic/tandem mass spectrometric (LC/MS-MS) method specifically designed for the screening of synthetic glucocorticosteroids in human urine. The method is designed to recognize a common mass spectral fragment formed from the particular portion of the molecular structure that is common to all synthetic glucocorticosteroids and that is fundamental to their pharmacological activity. As such, the method is also suitable for detecting unknown substances, provided they contain the portion of the molecular structure selected as the analytical target. The effectiveness of this approach was evaluated on seventeen synthetic glucocorticosteroids. Urine samples, including blank urines spiked with one or more synthetic glucocorticosteroids, were treated according to a standard procedure (enzymatic hydrolysis, liquid/liquid extraction and evaporation to dryness) and analyzed using LC/MS-MS with electrospray ionization (ESI). MS-MS acquisition was carried out in a precursor ion scan, and the results were compared with those obtained by a previously developed reference technique based on acquisition in the multiple reaction monitoring (MRM) mode. All of the glucocorticosteroids considered in this study are clearly detectable in urine, with a limit of detection in the concentration range 5-20 ng/mL, depending on the glucocorticosteroid structure. The proposed method is therefore suitable for the detection of glucocorticosteroids in urine samples taken for "in competition" sport anti-doping control tests, matching the requirements of the World Anti-Doping Agency (WADA) for accredited anti-doping laboratories.