Multiclass method for the quantification of 92 veterinary antimicrobial drugs in livestock excreta, wastewater, and surface water by liquid chromatography with tandem mass spectrometry.
In this work, an ultra high performance liquid chromatography-high resolution mass spectrometry (UHPLC-HRMS) methodology is proposed for the multi-class multi-residue screening of banned and unauthorized veterinary drugs in bovine urine, using an Orbitrap Exactive™ analyzer working at a resolving power of 50,000 FWHM in full scan, both in positive and negative mode. The method currently covers 87 analytes belonging to different families such as steroid hormones, β-agonists, resorcylic acid lactones (RAL), stilbens, tranquillizers, nitroimidazoles, corticosteroids, NSAIDs, amphenicoles, thyreostatics and other substances such as dapsone. A database including the elemental composition, the polarity of acquisition, retention time and expected adducts was built for the targeted analysis, and a high mass accuracy (<5 ppm) was set as one of the identification criteria. After comparing different sample preparation procedures, QuEChERS was selected as the most appropriate methodology. An efficient separation of analytes was achieved using ultra high performance liquid chromatography with a column packed with sub-2 μm particles. The performance of the method has been evaluated in accordance with the EU guidelines for the validation of screening methods for the analysis of veterinary drugs residues. The screening target concentrations were established between 0.2 μg/l and 20 μg/l, demonstrating the usefulness of UHPLC-HRMS as an ideal tool for compliance monitoring in regulatory laboratories.