Abstract: The objective of this study was to establish a method for detecting the residue of dicamba in cow milk by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The sample was extracted with 0.5% formic acid in acetonitrile, and the extract was purified by sodium chloride salting out, and separated on an Acquity UPLC BEH C18 column (100 mm × 2.1 mm, 1.7 μm) by gradient elution using a mobile phase composed of acetonitrile and 0.01% formic acid aqueous solution. Identification and quantification were achieved using an electrospray ionization source in the negative ion mode with multiple reaction monitoring (MRM). Under optimized pretreatment and instrumental conditions, good linearity was observed in the concentration range of 5.0–250.0 μg/L with correlation coefficient (r) more than 0.999. The limit of detection (LOD) and limit of quantification (LOQ) of the proposed method were 5 and 10 μg/kg, respectively. The recoveries of dicamba at spiked concentration levels of 10, 20 and 200 μg/kg were 104.3%, 101.5% and 96.2% with relative standard deviations (n = 6) of 3.0%, 2.0% and 1.5%, respectively. This method is simple, accurate, repeatable, and suitable for the rapid detection of dicamba in milk.

Key words: high performance liquid chromatography-tandem mass spectrometry; dicamba; milk; rapid detection

摘要： 建立一种高效液相色谱-串联质谱检测牛乳中麦草畏残留的方法。牛乳样品经体积分数0.5%甲酸乙腈溶液提取，氯化钠盐析净化，采用Acquity UPLC BEH C18色谱柱（100 mm×2.1 mm，1.7 μm）分离，以乙腈- 0.01%甲酸溶液为流动相进行梯度洗脱。采用电喷雾离子源负离子模式，多反应监测模式下进行定性和定量分析。结果表明：通过优化前处理方法和仪器条件，麦草畏在质量浓度5.0～250.0 μg/L范围内线性关系良好，相关系数（r）＞0.999；该方法的检出限和定量限分别为5、10 μg/kg，在3 个不同麦草畏添加水平（10、20、200 μg/kg）（n=6）下，加标回收率分别为104.3%、101.5%和96.2%，相对标准偏差分别为3.0%、2.0%和1.5%。该方法操作简单、结果准确、重复性好，适用于牛乳中麦草畏残留的检测。

关键词: 高效液相色谱-串联质谱；麦草畏；牛乳；快速检测