Effects of the Adulteration Technique on the Near-Infrared Detection of Melamine in Milk Powder
Effects of the Adulteration Technique on the Near-Infrared Detection of Melamine in Milk Powder
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DOI：
10.1021/acs.jafc.7b02083
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发表时间：
2017-07-19
影响因子：
6.1
通讯作者：
Moore, Jeffrey C.
中科院分区：
文献类型：
--
作者：
Scholl, Peter F.;Bergana, Marti Mamula;Moore, Jeffrey C.
《美国药典公约》领导了一个国际合作项目，以开发一个检测奶粉掺假的筛选方法和参考标准工具箱。在掺假奶粉标准品的研制过程中，联合收割机与牛奶的混合方法对三聚氰胺的近红外光谱产生了意想不到的强烈影响。三聚氰胺在1468 nm处的显著吸收带保留干混脱脂奶粉时，但消失在湿混混合物，其中喷雾干燥的奶粉样品从溶液中制备。使用偏振光显微镜，拉曼光谱，介电弛豫光谱，X-射线衍射和质谱分析表明，湿混合促进可逆的和早期的美拉德反应与乳糖，负责三聚氰胺的近红外光谱的差异湿和干混合样品。仅基于干混参比标准品的目标检测估计值可能会高估湿混样品中的近红外检测能力，这是由于以前忽略了三聚氰胺氢键状态变化、与乳糖共价络合以及湿混样品中产生的较低但更均匀的三聚氰胺局部浓度分布所产生的基质效应。用于掺入潜在掺假物的技术可以确定牛奶参考标准是否适合与快速检测方法一起使用。
The United States Pharmacopeial Convention has led an international collaborative project to develop a toolbox of screening methods and reference standards for the detection of milk powder adulteration. During the development of adulterated milk powder reference standards, blending methods used to combine melamine and milk had unanticipated strong effects on the near-infrared (NIR) spectrum of melamine. The prominent absorbance band at 1468 nm of melamine was retained when it was dry-blended with skim milk powder but disappeared in wet-blended mixtures, where spray-dried milk powder samples were prepared from solution. Analyses using polarized light microscopy, Raman spectroscopy, dielectric relaxation spectroscopy, X-ray diffraction, and mass spectrometry indicated that wet blending promoted reversible and early Maillard reactions with lactose that are responsible for differences in melamine NIR spectra between wet- and dry-blended samples. Targeted detection estimates based solely on dry-blended reference standards are likely to overestimate NIR detection capabilities in wet-blended samples as a result of previously overlooked matrix effects arising from changes in melamine hydrogen-bonding status, covalent complexation with lactose, and the lower but more homogeneous melamine local concentration distribution produced in wet-blended samples. Techniques used to incorporate potential adulterants can determine the suitability of milk reference standards for use with rapid detection methods.