基于同位镀铋技术的茶叶及其浸出物中铅含量的测定

Determination of Lead Content in Tea and its Extract Based on the Technigue of Situ-plate Bismuth Film

以铋膜修饰玻碳电极为工作电极,采用差分脉冲溶出伏安法对茶叶及茶叶浸出物中微量Pb^(2+)进行分析。结果表明,Pb^(2+)在5~300μg·L^(-1)范围内与峰电流呈良好的线性关系,检出限为0.39μg·L^(-1),相对标准偏差为1.98%(n=11),线性方程为I_p=0.023 6ρ(Pb^(2+))-0.098 4,相关系数r=0.999 2,茶叶样品中铅含量为0.53~2.98 mg·kg^(-1),加标回收率为91.5%~113.5%;茶叶浸出物中未检出铅,加标回收率在93.6%~99.5%。

Bismuth film modified glassy carbon electrode was used for working electrode to determine trace Pb2 ＋in the tea and water extraction by differential pulse stripping voltammetry（DPSV）. The results showed that there was a good linear relationship between peak current and concentration of Pb2＋in the range of 5-300 μg·L-1,the regression equation was Ip=0.023 6 ρ（Pb2＋）-0.098 4, and the detection limit was 0.39 μ g·L-1, RSD（n=11）was 1.98% and correlation coefficient r was 0.999 2. The rang of Pb2＋contents in tea was 0.53-2.98 mg·kg-1. The standard addition recovery for Pb2＋in tea and its extraction ranged from 91.5%-113.5% and 93.6%-99.5%,respectively.