Abstract: In this study, we aimed to establish a method for the determination of six pesticide residues in milk by quick, easy, cheap, effective, rugged, safe (QuEChERS) extraction combined with ultra high performance liquid chromatography-tandem mass spectrometry. Milk samples were extracted with acetonitrile, purified by the QuEChERS approach, and the extract was then blown down to dryness using a stream of nitrogen gas and re-dissolved. The liquid chromatographic separation was achieved by gradient elution using a mobile phase consisting of acetonitrile and 0.1% formic acid in water. The analysis was carried out using positive ion electrospray ionization under the multiple reaction monitoring mode. The external standard method was used for quantification. Excellent linearities were achieved for all target analytes in the range of 1.0–40.0 μg/L with correlation coefficients greater than 0.995. The limit of detection was 0.1 μg/kg, and the limit of quantification was 1.0 μg/kg. The average recoveries of the six pesticide residues from blank milk samples at three spiked concentration levels of 1.0, 2.5 and 5.0 μg/kg ranged from 76.5% to 113.7% with relative standard deviations (RSDs) of 1.5%–6.1%. The proposed method was simple, accurate, efficient and suitable for the rapid screening and quantitative analysis of pesticide residues in milk.

Key words: milk; ultra high performance liquid chromatography-tandem mass spectrometry; pesticide residues; determination

摘要： 建立超高效液相色谱-串联质谱法检测牛乳中6 种农药残留量的方法。用乙腈对牛乳进行提取，应用QuEChERS方法进行净化处理，氮吹后复溶，采用C18色谱柱梯度洗脱方式进行液相色谱分离，乙腈和体积分数0.1%甲酸-水溶液为流动相，采用电喷雾离子源正离子模式、多反应监测模式进行检测，外标法定量。结果表明：在1.0～40.0 μg/L质量浓度范围内待测物线性良好，标准曲线相关系数均大于0.995，检出限均为0.1 μg/kg，定量限均为1.0 μg/kg；于不含农药残留的牛乳中添加1.0、2.5、5.0 μg/kg 3 个水平的6 种农药标准品，进行加标回收实验，6 种农药的平均加标回收率为76.5%～113.7%，相对标准偏差为1.5%～6.1%。该方法简单、准确、高效，可用于牛乳样品中6 种农药残留的快速筛查和定量。

关键词: 牛乳；超高效液相色谱-串联质谱；农药残留；检测