Comprehensive screening of anabolic steroids, corticosteroids, and acidic drugs in horse urine by solid-phase extraction and liquid chromatography–mass spectrometry

This paper reports two highly efficient liquid chromatography–mass spectrometry (LC–MS) methods for the screening of anabolic steroids, corticosteroids, and acidic drugs for the purpose of doping control in equine sports. Sample extraction was performed using a mixed-mode C8-SCX solid-phase extraction (SPE) cartridge. The first eluted fraction (acidic/neutral fraction) was base-washed and the resulting organic extract was used for the screening of anabolic steroids and corticosteroids by LC–MS using multiple reaction monitoring (MRM) in the positive electrospray ionisation (ESI) mode. The remaining aqueous extract was re-adjusted to pH 6 and acidic drugs were recovered by liquid/liquid extraction. Detection was again achieved using LC–MRM but in the negative ESI mode. A total of 40 anabolic steroids and corticosteroids, and over 50 acidic drugs, including some cyclooxygenase-2 (COX-2) inhibitors, oxicams, anti-diabetics, sedatives, diuretics and Δ9-tetrahydro-11-norcannabinol-9-carboxylic acid, could be covered by the two LC–MS methods. Both methods utilized a high efficiency reversed-phase column (3.3 cm L × 2.1 mm I.D. with 3 μm particles) coupled with a fast-scanning triple-quadrupole mass spectrometer to achieve fast turnaround times. The overall turnaround times for both methods were 10 min, inclusive of post-run and equilibration times.