Nestle Research Centre, Nestec Ltd., Vers-chez-les-Blanc, Lausanne 26, Switzerland.
J Agric Food Chem. 2009 Aug 26;57(16):7186-93. doi: 10.1021/jf901355v.
An isotope dilution liquid chromatography-electrospray ionization tandem mass spectrometry method for the simultaneous determination of melamine and cyanuric acid in cow's milk (range of 0-0.3 mg/kg) and milk-based infant formulas (ranges of 0-0.3 and 0-2.0 mg/kg) is described. This quantitative method entails simple sample preparation, limited to a protein precipitation in acetonitrile/water followed by a centrifugation and direct injection of the supernatant. Selected reaction monitoring of two diagnostic transition reactions for each analyte and each corresponding ((13)C(3),(15)N(3))-labeled compound enables selective and confirmatory detection. Acquisition was performed sequentially in the negative ion mode for cyanuric acid, while in the positive mode for melamine within the same run. Validation of the method was conducted according to European Union criteria (CD 2002/657/EC). Internal standard-corrected recoveries were within the 99-116% range for both analytes in the two matrix types, along with repeatability and intermediate reproducibility values of <or=12.3 and <or=31.2%, respectively. LODs were 0.025 and 0.050 mg/kg for melamine and cyanuric acid, respectively, whereas LOQs, set arbitrarily at the lowest fortification level, were 0.05 and 0.10 mg/kg for melamine and cyanuric acid, respectively. CCalpha and CCbeta, at the 1 mg/kg maximum limit (ML) for infant formula powder endorsed by WHO, were respectively 1.03 and 1.05 mg/kg for melamine and 1.04 and 1.09 mg/kg for cyanuric acid.
本文描述了一种用于同时测定牛奶（0-0.3mg/kg）和婴幼儿配方乳粉（0-0.3 和 0-2.0mg/kg）中三聚氰胺和三聚氰酸的同位素稀释液相色谱-电喷雾串联质谱法。该定量方法需要进行简单的样品前处理，仅限于用乙腈/水进行蛋白质沉淀，然后离心，直接将上清液进样。每个分析物和每个相应的 ((13)C(3),(15)N(3))-标记化合物都选择两个诊断转换反应进行选择反应监测，实现选择性和确证检测。在同一运行中，为了检测三聚氰酸，采用负离子模式，而检测三聚氰胺则采用正离子模式。方法验证符合欧盟标准（CD 2002/657/EC）。两种基质类型中，两种分析物的内标校正回收率均在 99-116%范围内，重复性和中间精密度值分别小于或等于 12.3%和 31.2%。三聚氰胺和三聚氰酸的检出限（LOD）分别为 0.025 和 0.050mg/kg，而定量限（LOQ）则设定为最低添加水平，分别为 0.05 和 0.10mg/kg。在世界卫生组织（WHO）认可的婴幼儿配方粉 1mg/kg 的最大限量（ML）下，CCalpha 和 CCbeta 分别为 1.03 和 1.05mg/kg 用于三聚氰胺，1.04 和 1.09mg/kg 用于三聚氰酸。
