超高效液相色谱-串联质谱法同时测定牛奶和奶粉中的二氰二胺、三聚氰胺和三聚氰酸

建立了一种超高效液相色谱-串联质谱法测定牛奶和奶粉中二氰二胺(DCD)、三聚氰胺(MEL)和三聚氰酸(CY)的分析方法。样品用5%(质量分数)三氯乙酸水溶液提取,无需净化和浓缩,用Acquity UPLC HSS T3色谱柱(50 mm×2.1 mm, 1.8 μm)分离,以乙腈和乙酸铵作为流动相进行梯度洗脱,电喷雾正、负离子(ESI^±)模式同时电离,多反应监测模式进行检测。结果表明:在5.0～200.0 μg/L范围内线性关系良好(r≥0.995)。牛奶中3种化合物在0.02、0.10、0.20 mg/kg的添加回收率为60.0%～105.8%,相对标准偏差(RSD, n=6)为4.2%～13.6%;奶粉中3种化合物在0.05、0.10、0.20 mg/kg的添加回收率为78.0%～115.0%, RSD (n=6)为2.7%～7.5%。牛奶中方法的定量限(信噪比为10)为0.02 mg/kg,奶粉中方法的定量限为0.05 mg/kg。该方法简单、快速、灵敏、准确,适合于牛奶、奶粉等乳及乳制品中DCD、MEL和CY的快速、高灵敏的分析检测。

Determination of dicyandiamide,melamine and cyanuric acid in milk and milk powder by ultra performance liquid chromatography-tandem mass spectrometry

A method for the determination of dicyandiamide (DCD), melamine (MEL) and cyanuric acid (CY) in milk and milk powder has been developed by ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). After extracted by 5% (mass fraction) trichloroacetic acid, the samples were loaded onto an Acquity UPLC HSS T3 column (50 mm×2.1 mm, 1.8 μm) and separated using acetonitrile and ammonium acetate as mobile phases in a gradient elution mode. The electrospray was operated in the positive mode and negative mode, and monitored by the multiple reaction monitoring (MRM) mode. The calibration curves showed a good linearity in the range of 5.0-200.0 μg/L, and the correlation coefficients (r) were not less than 0.995. When the spiked levels were 0.02, 0.10 and 0.20 mg/kg, the recoveries of DCD, MEL and CY in milk ranged from 60.0%. to 105.8%, with the relative standard deviations (RSDs) of 4.2%-13.6%; while the spiked levels were 0.05, 0.10 and 0.20 mg/kg in milk powder, the recoveries ranged from 78.0% to 115.0% with the RSDs of 2.7%-7.5%. The limits of quantification (LOQs, S/N=10) were 0.02 mg/kg for milk samples and 0.05 mg/kg for milk powder samples. The results indicate that the method is simple, rapid, sensitive and suitable for the qualitative and quantitative analyses of DCD, MEL and CY in milk and dairy product samples.