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

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 I_p=0.023 6ρ(Pb²⁺)-0.098 4, and the detection limit was 0.39 μg·L^-1, RSD (n=11) was 1.98% and correlation coefficient rwas 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.