建立了牛奶中20 种常用兽药残留量的超高效液相色谱-串联质谱测定法。样品经乙腈处理洗涤后过Oasis PRiME HLB固相萃取柱净化,氮吹浓缩后经LC-MS/MS测定。采用ACQUITY UPLC ®HSS T3色谱柱分离,以0.2%甲酸水-0.2%甲酸乙腈为流动相,梯度洗脱;质谱采用电喷雾正离子模式离子化,多反应监测模式（MRM）监测,外标法定量。结果表明,20 种兽药在0.5~10.0 ng/mL浓度范围内线性关系良好,相关系数R²均大于0.991。该方法检出限为0.02~0.4 μg/kg,定量限为0.05~1.2 μg/kg。牛奶中20 种兽药在添加量为2.0 μg/kg时,平均回收率为60.6%~90.4%;添加量为10.0 μg/kg时,平均回收率为64.8%~93.2%。该方法简便快捷,准确度和灵敏度高,可作为牛奶中20 种常用兽药残留量的快速筛查和定量方法。

To develop an analytical method for the determination of 20 veterinary drugs residues in milk by UPLC-MS/MS. The milk samples were extracted with acetonitrile,and cleaned up with Oasis PRiME HLB solid phase extraction column. The elution was gathered together and then concentrated under nitrogen gas flow. The target components were separated in a gradient elution mode using an ACQUITY UPLC ® HSS T3 column as stationary phase and 0.2% formic solution-0.2% formic acetonitrile as mobile phase,then identified and externally quantified by UPLC-MS/MS with electrospray ion source （ESI） under multi-reaction ion monitoring （MRM） mode. Results showed that the 20 veterinary drugs had good relationship in their respective linear ranges of 0.5~10.0 ng/mL,with correlation coefficients（R²）higher than 0.991. The limit of detection for this method were between 0.02 μg/kg and 0.4 μg/kg,and the limit of quantification for which were between 0.05 μg/kg and 1.2 μg/kg. The method was validated at spiked levels of 2.0 μg/kg and 10.0 μg/kg,with overall recoveries in ranges of 60.6%~90.4% and 64.8%~93.2%. The method was simple and convenient,efficient,accurate and sensitive,which could meet the requirements of screening and quantification for the 20 veterinary drugs used widely in milk.