稀释酸微波消解辅助分析红茶茶叶中微量元素

建立了稀释酸微波消解处理茶叶样品的新方法，并结合国外方法EPA6020对仪器和测定过程进行校准。采用微波消解-ICP-MS测定了8种红茶茶叶中16种微量元素（V、Cr、Mn、Fe、Co、Ni、Cu、Zn、As、Se、Sr、Ag、Cd、Cs、Ba、Pb）的质量分数，运用主成分分析法和箱线图研究16种微量元素的分布特征。结果表明，当微波消解酸为6 mL浓度2.1±0.2 mol/L的硝酸和2 mL 30%的双氧水溶液时，16种元素的回收率变化范围为90%~110%，线性相关系数R2>0.999 5，RSD<5%，而且检出限低，说明该稀释酸体系可以替代浓酸体系。Fe、Zn、Mn等大量人体必需微量质量分数均符合国家标准，但是有害重金属元素As质量分数均高于限量值，除了S1样品中Ba、Sr，S6样品中Se和S8样品中Ag质量分数表现异常外，16种微量元素质量分数在样品中整体分布较为集中。此外，已报道Cd元素的质量分数值是测定平均值的43.53倍，As元素质量分数平均值是已报道值的12.53 倍，结果说明在红茶茶叶的生产过程中As元素污染严重，有轻度的Cr污染，而Cd元素在红茶茶叶的种植、采摘、加工和运输过程中得到了很好的控制。研究也表明V、Sr、Cr、Ba、Fe、As和Zn为红茶茶叶的主成分元素，同时对8种红茶茶叶做出了综合评价得出S1为最佳选择。
A new method for microwave-assisting diluted acid digestion of tea leaves ，The paper calibrated the instrument and measurement process with EPA6020，It determined the content of the trace elements in black tea leaves by microwave digestion and ICP-MS，It analyzed the 16 kinds of trace and Mn et al，were lower than the limited value，elements（V，Cr，Mn，Fe，Co，Ni，Cu，Zn，As，Se，Sr，Ag，Cd，Cs，Ba and Pb） in 8 kinds of blacks tea leaves，besides，It analyzed the trace elements with the method of principal component analysis. Consequently，the concentration of diluted acid was 2.1±0.2 mol/L could replace concentrated acid，the recovery was 90%~110%，RSD was lower than 5%，and the limited detection was lower. The result turned out that the essential elements，including Sr，Fe，Zn but the content of As was more than the limited value.In generally，The centralized distribution of determining values except the samples of Ba，Sr in S1，Se in S6 and Ag in S8. besides，the reported value of Cd was 43.53 times more than the determined value，the determined value of As was 12.53 times more than the addition，It also showed that Pb，Cd，As and Cr were toxic and harmful elements，the content of Pb and Cr were reported value，the result showed that the pollution of As was more serious，Cr was a little pollution，but the Cd was well controlled in the planting，harvesting，processing and transportation. The research also showed that V，Sr，Cr，Ba，Fe，As and Zn were principal component elements. Besides，it made a comprehensive evaluation for 8 kinds of black tea leaves，the result proved that S1 was the best choice