Simultaneous determination of 38 veterinary antibiotic residues in raw milk by UPLC–MS/MS

•Thirty eight antibiotic residues were analyzed in raw milk by UPLC–MS/MS.•Extraction procedure of antibiotic residues in raw milk was optimized.•The proposed method achieves suitable detection limits, recoveries and precision.•The low LOQs were fit for trace analysis of antibiotic residues in raw milk.

A selective and rapid method has been developed to determine, simultaneously, 38 veterinary antibiotic residues in raw milk by ultra-high-performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS). One milliliter of raw milk was diluted with 0.5 mL water and 3 mL acetonitrile, then purified using an Oasis HLB cartridge. The eluates were evaporated by nitrogen drying and then reconstituted to 4 mL with water/acetonitrile (8:1) before being injected into the UPLC–MS/MS system. The results indicated recoveries of 68–118% for 14 β-lactams, 79–118% for eight quinolones, 71–106% for eight sulfonamides, 76–116% for four tetracyclines, 78–106% for three macrolides, and 88–103% for one lincosamides, with coefficients of variation less than 15% for intraday and interday precisions. The limit of quantification for all antibiotics was 0.03–10 μg kg−1. This methodology was then applied to field-collected real raw milk samples and trace levels of four antibiotics were detected.