Abstract: An ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for the quantitative determination of salicylic acid in milk and dairy products was developed. The sample was extracted with 1% acidified acetonitrile, and then the extract was purified by solid-phase extraction (SPE) with an HLB cartridge. The separation was performed on an Acquity UPLC BEH C18 chromatographic column (50 mm × 2.1 mm, 1.7 μm）with gradient elution using 0.1% aqueous formic acid-acetonitrile as the mobile phase. The target compound was monitored under the negative ion mode with an electrospray ionization (ESI) source and quantified by external standard method. The results demonstrated that the linear range of the proposed method was from 0.5 to 50.0 ng/mL with a correlation coefficient (R2) > 0.999. The average recovery of salicylic acid in different matrixes spiked at low, medium and high levels varied from 68.3% to 111.7%, and the relative standard deviations (RSDs) of precision were between 3.3% and 15.2%. The limits of detection (LODs) were 5.0 and 10.0 μg/kg in milk and milk powder, respectively. This method can meet the requirements for the determination of different salicylic acid levels in milk and dairy products.

Key words: ultra performance liquid chromatography-tandem mass spectrometry; salicylic acid; milk; milk powder; dairy products

摘要： 建立一种超高效液相色谱-串联质谱法同时测定牛乳、酸乳、乳粉及冷冻饮品中水杨酸含量的方法。样品 经1%酸化乙腈提取，HLB固相萃取小柱净化，经Acquity UPLC BEH C18色谱柱（50 mm×2.1 mm，1.7 μm）分离， 以0.1%甲酸水溶液-乙腈为流动相，梯度洗脱，电喷雾离子源负离子模式、多反应监测模式测定，外标法定量。结 果表明：水杨酸在质量浓度0.5～50.0 ng/mL范围内线性关系良好，相关系数（R2）大于0.999；在不同基质的低、 中、高3 个水平加标实验中，水杨酸的平均回收率为68.3%～111.7%，相对标准偏差为3.3%～15.2%；液体乳中定量 限为5.0 μg/kg，乳粉中为10.0 μg/kg，可以满足乳及乳制品中不同水杨酸含量水平的定量测定要求。

关键词: 超高效液相色谱-质谱联用；水杨酸；牛乳；乳粉；乳制品