利用电感耦合等离子体质谱检测牛奶中的微量元素

Using Inductively Coupled Plasma Mass Spectrometry on Detecting the Trace Elements in Milk

牛奶中微量元素的含量是乳制品安全和质量的重要组成部分。如牛奶中低含量的铬是人体必需的微量元素,超过一定含量后就会对人体的健康造成危害。作者建立了用电感耦合等离子体质谱(inductively coupled plasma mass spectrometry,ICP-MS)检测生鲜乳中Fe、K、Ca、Na、Mg、Ag、Al、As、Ba、Be、Cd、Co、Cr、Cu、Mn、Mo、Ni、Pb、Sb、Se、Tl、V、Zn、Th、U、Hg和Sn的新方法。采用微波消解法破坏牛奶中的有机物,利用ICP-MS法测定其含量,分析元素的同位素一般选择丰度最大的,除非存在相同质量原子簇和同量异位素的干扰。该方法验证采用国家标准物质脱脂奶粉GBW 08509和加标回收2种方法,试验证明在内标溶液中加入异丙醇能消除积碳的干扰,且对样品中砷和硒等元素测定的精确度和重现性也大为改善。

The level of trace elements is an important component of safety and quality in milk.While certain elements such as chromium is essential at low level,an excess can result in deleterious effects on human health.This paper described a new method for demonstrating the levels of Fe,K,Ca,Na,Mg,Ag,Al,As,Ba,Be,Cd,Co,Cr,Cu,Mn,Mo,Ni,Pb,Sb,Se,Tl,V,Zn,Th,U,Hg and Sn in raw cow's milk,using an inductively coupled plasma mass spectrometry(ICP-MS).Using microwave digestion method destroyed the organic matter in milk.Each milk sample was mineralised by using a microwave-assisted digestion procedure.Concentrations of trace elements in digested milk samples were measured by ICP-MS.The selected isotopes were in general the most abundant ones of each element,except in cases where polyatomic or isobaric interferences were detected.Method validation was performed by measuring a GBW 08509non-fat milk powder and through the use of recovery experiments.Plasma-related matrix effects are also investigated in this paper.The study shows that addition of a set concentration of isopropanol to internal standard solution could eliminate the interference of carbon deposition.The accuracy and reproductibility of the determination of As and Se by ICP-MS was improved by this method.