Determination of 28 Drug Residues in Lamb by Modified QuEChERs-Ultra High Performance Liquid Chromatography Tandem Mass Spectrometry

Drug abuse is very easy to cause the residues of harmful substances in food of animal origin, which not only does direct harm to human health, but also does great harm to the development of animal husbandry and the ecological environment. Therefore, the detection of residual drugs in animal-derived food is of great significance to ensure food safety. In this study, 28 drugs in lambs were simultaneous determined by modified QuEChERs combined with ultra-high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) based on magnetic multi-walled carbon nanotubes (Fe₃O₄-MWCNTs). Under the optimized separation and detection conditions, the effects of different dehydrated salts (MgSO₄, Na₂SO₄) and metal chelating agents (Na₂EDTA) on the drug recoveries were investigated. Then, the Fe₃O₄-MWCNTs adsorbent dosages on the purification efficiency were evaluated in terms of drug recoveries and residual matrix masses as well as decoloration effects. The Fe₃O₄-MWCNTs showed better or equivalent purification performance results than commercial purification adsorbents (C18, PSA, GCB). The results showed that the linear relationship was good for all monitored drugs in the range of 15-500 μg/kg, the correlation coefficient was better than 0.999. By constructing matrix-matched curves and solvent standard curves, the calculated matrix effects (MEs) were located within -9.7%-14.2%, demonstrating its good matrix purification efficiency. Under three spiked concentrations (20, 100, 200 μg/kg), satisfactory recoveries were obtained in the range of 60.2%-114.3%, 68.9%-106.7% and 60.4%-94.8%, respectively, which demonstrated the good accuracy of the method in quantitative analysis. The method precision was validated by intra- and inter-day repetitive experiments on the same day or on the three consecutive days. The obtained intra- and inter-day relative standard deviations (RSDs) were no more than 9.9% and 13.0%, respectively, which indicated the good precision and robustness of the developed method. The limits of detection (LODs) and limits of quantitation (LOQs) were obtained in the range of 0.1-5.0 μg/kg and 0.3-12.0 μg/kg, respectively, which were sensitive enough to analyze the monitored drugs with concentrations exceeding their corresponding maximum residue limits. This method has good applicability in qualitative and quantitative analysis of 28 drug residues in lambs, and can provide a strong technical support for rapid detection of food hazards in other animal origins.