Development of a multi-residue method for fast screening and confirmation of 20 prohibited veterinary drugs in feedstuffs by liquid chromatography tandem mass spectrometry

•20 prohibited veterinary drugs.•Multiclass drugs in swine, chicken and fish feedstuffs.•QuEChERS approach.•A sensitive and reliable LC–MS/MS method is firstly developed.

A simple multiresidue method was developed for detecting and quantifying twenty analytes from 5 classes of prohibited veterinary drugs (β-agonists (9), anabolic hormones (4), quinoxalines (4), tranquilizers (1), cyproheptadine, and clonidine in animal feeds using a QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) approach. Feed samples were extracted by ultrasonic-assisted extraction with a mixture of methanol–acetonitrile (50:50, v/v), followed by a cleanup using a dispersive solid-phase extraction with PSA (primary secondary amine). Target compounds were separated and determined by a liquid chromatography tandem quadrupole mass spectrometer operating in positive electrospray ionization mode, using multiple reaction monitoring (MRM). The recoveries of these compounds were between 56.7% and 103% at three spiked levels. The repeatability was lower than 10%, whereas reproducibility was no more than 15% except for nandrolone (17% at 10 μg kg−1) and diazepam (19% at 10 μg kg−1). Decision limits (CCαs) and detection capabilities (CCβs) ranged from 0.42 to 5.74 μg kg−1 and 5.70–9.81 μg kg−1, respectively. The method was successfully applied to screening of real samples obtained from local feed markets and confirmation of the suspected target analytes.