Abstract: In this study, a high performance liquid chromatography tandem time-of-flight mass spectrometry (HPLC-TOF-MS/MS) method was established for the high-throughput determination of 174 veterinary drug residues in raw milk. The target compounds were extracted with acetonitrile and purified by freezing. A Poroshell 120 EC-C18 column (3.0 mm × 150 mm, 2.7 μm) was used for the separation of the target compounds with a mobile phase consisting of 0.1% formic acid in water and methanol via gradient elution. The analytes were detected with an electrospray ionization source (EIS) in the positive ion mode. The results showed that the method had a good linearity (R2 > 0.990 0) and low limits of detection (LOD) (1–10 ng/g) for 114 pesticide compounds. The average recoveries for 99 of these ranged from 70% to 130% with relative standard deviation (RSD) from 1.03% to 9.65% at quality control concentration levels. The method was successfully applied in the screening of veterinary drug residues in raw milk with high efficiency and sensitivity.

Key words: raw milk, veterinary drug residues, high performance liquid chromatography tandem time-of-flight mass spectrometry (HPLC-TOF-MS/MS), high throughput