Determination of trenbolone and its metabolite in bovine fluids by liquid chromatography–tandem mass spectrometry

A liquid chromatographic–tandem mass spectrometric (LC–MS–MS) method has been developed for the determination of trenbolone in bovine urine and serum. The aim was a control of the misuse of trenbolone in food-producing animals. The procedure involved, in both cases, a preliminary solid-phase clean-up followed by a liquid–liquid extraction for urine samples after a preliminary enzymatic hydrolysis. The extracts have been directly analysed by reversed-phase LC–MS–MS in selected reaction monitoring (SRM), acquiring two diagnostic product ions from the chosen precursor [M+H] +. The procedures were validated across the concentration range of 1–1500 ng/ml. The linearity, the inter- and intra-day accuracy and precision have been determined. The procedure was specific and the accuracy values were better than 20% at the limit of quantitation of spiked samples. The limit of quantification (LOQ) and the limit of detection (LOD) were, respectively, 1 ng/ml and 350 pg/ml for urine and serum. According to the draft, SANCO/1805/2000, we determined the decision limit CC α and the detection capability CC β. The recovery values for urine ranged from 87 to 128%, and for plasma the recovery was 70±4%. The procedure proved to be simple and suitable for routine and confirmatory purposes such as those developed for residue studies.