基于咖啡环效应的牛奶中非法添加剂拉曼光谱检测方法

The problem of illegal additives in milk represents one of the prominent contradictions that affect the food safety of China, attracting the great concern of the whole society. Detection of qualitative and quantitative information of illegal additives in milk is the only way to discriminate the edible safety of milk accurately. However, most of the current analytical methods require complicated sample pretreatment, which is very time-consuming, laborious, expensive and complicated, making the detection throughput of milk samples too limited to fit the currently severe situation of edible safety of milk. The development of new efficient detection method is thus imperative. In this regard, the coffee ring effect (CRE) is innovatively introduced for detection of milk safety. The CRE is a new physics phenomenon of efficient separation and enrichment that concentrates the solutes to the ring edge according to their molecular size through normal evaporation process, thus improving the sensitivity of overall detection drastically. On the basis of making full use of the CRE characteristics of separation and enrichment, the confocal micro-Raman spectroscopy with the properties of high resolution and high throughput is then integrated to establish the novel method of coffee ring deposition Raman spectral diagnosis (CRDRSD), which is hopeful to screen multiple most common illegal additives in milk, e.g. melamine, hydroxyproline, sodium thiocyanate, zeranol and so on, simultaneously. CRDRSD possesses the advantages of high sensitivity and high throughput, together with the easy operation, thus providing a novel idea and approach for rapid screening of edible safety of milk, milk powder and such dairy products.

牛奶中非法添加剂问题作为我国食品安全的突出矛盾之一，已引起全社会的高度关注。只有明确非法添加剂在牛奶中的定性定量信息，才能准确判断牛奶的食用安全。现有分析方法大都需要繁琐的样品前处理，费时、费力、费用高且操作复杂，导致牛奶样品检测通量有限，难以适应当前牛奶食用安全的严峻形势，因此，发展新型高效检测方法势在必行。本项目创新性地将咖啡环效应引入牛奶安全检测中，该效应是一种高效分离富集的物理新现象，通过正常蒸发过程将溶质按照分子大小集中到环状边缘，极大地提高了整体检测的灵敏度。在充分利用咖啡环效应分离富集特性的基础上，结合高分辨、高通量的共聚焦显微拉曼光谱，建立咖啡环沉积拉曼光谱诊断新方法，有望实现牛奶中最常见的三聚氰胺、羟脯氨酸、硫氰酸钠、玉米赤霉醇等多种非法添加剂的同时筛查。咖啡环沉积拉曼光谱检测具备高灵敏、高通量的优点，操作简便，为牛奶、奶粉等乳制品食用安全的快速筛查提供了新的思路和方法。

项目主要针对牛奶中三聚氰胺、羟脯氨酸、硫氰酸钠、玉米赤霉醇等常见非法添加剂的检测问题，创新性地将咖啡环效应引入牛奶安全检测中，借助该效应的分离富集特性，结合高分辨、高通量的拉曼光谱成像技术，建立咖啡环沉积拉曼光谱诊断新方法(CRDRSD)。项目依次渐进地探索不同实验条件及参数对CRDRSD方法的影响，并深入探讨咖啡环分离富集特性、复杂体系光谱解析、CRDRSD方法重现性等关键问题，进而明确CRDRSD方法的检测机理及实际适用范围。大量的实验数据表明，CRDRSD方法在单滴样品消耗量的水平上，实现对牛奶中多种有害污染物的高效检测，其检测灵敏度优于0.5 mg/kg，有效满足牛奶中大多数非法添加剂检测需求。该方法仅依赖于液滴正常的蒸发过程，无需额外条件，使得整个检测过程简单、高效，具备良好的拓展性，可为牛奶、奶粉等乳制品食用安全的低成本诊断提供新的思路和方法。此外，为验证CRDRSD方法的有效性，课题组还将该方法应用于鸡蛋等食品体系的风险组分检测，结果表明，CRDRSD方法具备良好的检测灵敏度和重现性，进而为食品安全的快速检测提供一种新方法。