Abstract: A method for the determination of 25 β-receptor agonist residues in milk and dairy products was established based on ultra-high performance liquid chromatography-tandem mass spectrometry. Samples were enzymatically hydrolyzed in 0.2 mol/L ammonium acetate solution at pH 5.2 for 16 h. After the removal of fat and protein through glass fiber filter paper, the filtrate was purified by solid phase extraction (SPE) using a PRiME MCX solid phase extraction column, and separated on a Waters BEH C18 column (100 mm × 2.1 mm, 1.7 μm) by gradient elution using a mobile phase composed of acetonitrile and 0.1% formic acid in water. Mass spectrometry was performed using an electrospray ionization source (ESI) in the positive ion mode with multiple reaction monitoring (MRM), and quantitative determination was performed using the internal standard method. The proposed method showed good linearity for all analytes in the concentration range of 0.2–50.0 ng/mL with coefficients of determination (R2) greater than 0.996; the recoveries ranged from 80.3% to 106.2% with relative standard deviations (RSDs) of 0.6%–8.5% (n = 6). The limits of detection (LOD) were 0.05–0.10 μg/kg, and the limits of quantification (LOQ) were 0.10–0.20 μg/kg. This method is simple, efficient and suitable for the determination of the 25 β-receptor agonist residues in milk and dairy products.

Key words: ultra-high performance liquid chromatography; milk; dairy products; β-receptor agonists

摘要： 基于超高效液相色谱-串联质谱技术，建立牛乳及乳制品中25 种β-受体激动剂的测定方法。样品经37 ℃酶解16 h、0.2 mol/L乙酸铵溶液（pH 5.2）提取、玻璃纤维滤纸除去脂肪和蛋白质，PRiME MCX固相萃取柱净化，并采用Waters BEH C18柱（100 mm×2.1 mm，1.7 μm）分离，以乙腈和0.1%甲酸水溶液作为流动相进行梯度洗脱，采用电喷雾离子源正离子、多反应监测模式，内标法定量。结果表明：在0.2～50.0 ng/mL质量浓度范围内，25 种β-受体激动剂线性关系良好，决定系数（R2）大于0.996；加标回收率为80.3%～106.2%，相对标准偏差为0.6%～8.5%（n＝6），检出限为0.05～0.10 μg/kg，定量限为0.10～0.20 μg/kg。该方法简便、高效，适用于牛乳及乳制品中25 种β-受体激动剂的测定。

关键词: 超高效液相色谱-串联质谱法；乳；乳制品；β-受体激动剂