超高效液相色谱-串联质谱法测定牛乳中21种β-兴奋剂

建立超高效液相色谱-串联质谱法同时测定牛乳中21 种β-兴奋剂残留量。样品经酶解、固相萃取柱净化，采用Acquity UPLC BEH C18色谱柱（50 mm×2.1 mm，1.7 μm）分离，以0.1%甲酸-10%甲醇水溶液为流动相梯度洗脱，在电喷雾离子源正离子模式下，采用多反应监测模式，对21 种β-兴奋剂进行定性和定量分析。结果表明：该方法的定量限为0.05 μg/kg，在0.05、0.10、0.50 μg/kg 3 个不同添加水平下，平均回收率为61.0%～124.3%，相对标准偏差为2.39%～10.66%；该方法稳定、准确、灵敏度高，可用于牛乳中21 种β-兴奋剂残留量检测。

Quantitative Determination of 21 β-Agonists in Milk by Ultra Performance Liquid Chromatography-Tandem Mass Spectrometry

An ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for the simultaneous quantitative determination of 21 β-agonists in milk. The samples were hydrolyzed and cleaned up a solid-phase extraction column. The analytes were separated by UPLC with an Acquity UPLC BEH C18 column (50 mm × 2.1 mm, 1.7 μm) using a gradient mobile phase consisting of 0.1% formic acid aqueous solution and methanol (10 : 90, V/V). Identification and quantification were achieved by UPLC-MS/MS with multiple reaction monitoring (MRM) under the positive ion mode The limit of quantitation of all β-agonists was 0.05 μg/kg. The average recovery varied from 61.0% to 124.3% at spiked concentration levels of 0.05, 0.10 and 0.50 μg/kg with relative standard deviations (RSDs) of 2.39%–10.66%. Our results demonstrate that the method is stable, accurate and sensitive, and can be used for the determination of the 21 β-agonists residues in milk.