An ultra performance liquid chromatography-tandem mass spectrometric method, with modified QuEChERS method for sample preparation, was developed for the determination of the 4 kinds of 29 banned and restricted veterinary drugs in chicken muscle, chicken liver, porcine muscle and porcine liver samples. The drugs were extracted with McIlvaine buffer solution and acetonitrile, then cleaned-up by modified QuEChERS method, and finally analyzed by ultra performance liquid chromatography-tandem mass spectrometry in multiple reaction monitoring mode via positive electrospray ionization. The method was validated at three fortification levels (LOQ level, 20 μg/kg and 50 μg/kg) in chicken muscle, chicken liver, porcine muscle and porcine liver samples. The validation results were as follows. The correlation coefficients of the standard calibration curves for the 29 veterinary drugs were all between 0.993 and 0.999 over their own concentration ranges. The average recoveries of the 29 drugs were between 71.5% and 93.2%, with the relative standard deviations (RSDs) between 0.8% and 7.7%. The limits of determination (S/N=3) of the drugs were between 0.3 and 3.0 μg/kg. The limits of quantification (S/N≥10) were 1.0 μg/kg for amantadine, 10.0 μg/kg for the tetracycline drugs, and 5.0 μg/kg for all the other drugs. It was indicated that the method developed is easy, sensitive, and has a good purification effect. The sensitivity, accuracy and precision of the method were all acceptable, and it can meet the requirements of the multiple residue analysis. So, this method can be further applied to investigate the veterinary drug residues in animal derived foods.
