Simultaneous Determination of 76 Veterinary Drugs and Their Metabolites in Pork by QuEChERS-Ultra High Performance Liquid Chromatography-Tandem Mass Spectrometry

In order to improve the efficiency of the detection of multiple veterinary drug residues in pork, a method for the simultaneous determination of 5 types of 76 veterinary drugs and their metabolites residues in pork, including quinolones, sulfonamides, nitroimidazoles, macrolides and benzimidazoles, was established by QuEChERS combined with ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The samples were extracted with acidified acetonitrile and salted out by anhydrous sodium sulfate. The extract was divided into two parts after purified by C₁₈ and anhydrous magnesium sulfate. One part was used for direct determination of the 22 weakly polar compounds, and the other part was concentrated by nitrogen blowing for the determination of the 54 strongly polar compounds. The 76 compounds were analyzed in multiple reaction monitoring (MRM) mode via electrospray ionization, and quantified by matrix matching external standard method. The results showed that the correlation coefficients were greater than 0.995, and the limits of quantification (LOQs) were lower than 10 μg/kg. The recoveries ranged from 61.3% to 96.2%, with the relative standard deviation (RSD) between 2.0% and 14.6%. The method was applied to 170 pork samples sold in the market, 23 samples of which were detected with 2 types of 5 veterinary drugs residues. The method was simple, rapid, accurate, reliable, and suitable for rapid screening and accurate detection of multiple veterinary drug residues in pork.