Screening of non-steroidal anti-inflammatory drugs, barbiturates and methyl xanthines in equine urine by gas chromatography–mass spectrometry

Abstract

A gas chromatographic–mass spectrometric (GC–MS) screening procedure for 23 acidic drugs in equine urine is described. With the GC–MS method fifteen anti-inflammatory drugs, five barbiturates and three methyl xanthines can be detected with good sensitivity and selectivity. The method consists of alkaline hydrolysis, extraction with organic solvent using salting-out, clean-up extraction, methylation and screening with GC–MS in selected-ion monitoring mode. The limit of detection is 10 µg l^–1 or lower, for most drugs.