聚邻苯三酚修饰电极选择性预富集与测定铋(Ⅲ)

Poly(pyrogallol) films on glassy carbon electrodes for selective preconcentration and determination of Bi(Ⅲ)

在pH 7的磷酸盐缓冲溶液中 ,氧化聚合邻苯三酚制得一稳定的水不溶性的膜粘附于玻碳电极的表面。此邻苯三酚膜修饰的玻碳电极被用于在一定电位下选择性预富集Bi(Ⅲ )。预富集的Bi(Ⅲ )在一定的电位下还原 ,再用微分脉冲阳极溶出伏安法测定。讨论了预富集、还原、溶出和清洗过程中的各种因素的影响。在最佳条件下 ,Bi(Ⅲ )浓度在 2 .5× 1 0 - 9～ 6.5× 1 0 - 6 mol/L范围内与阳极氧化峰电流呈线性 (富集 1 0min) ,相关系数为 0 9997。检测限为 1 .4× 1 0 - 1 0mol/LBi(Ⅲ ) (S/N =3,富集 1 0min)。对 5× 1 0 - 8mol/LBi(Ⅲ )平行测定 8次 ,相对偏差为 3.4%。方法可用于人发和指甲样品的测定。

Oxidative electropolymerization of pyrogallol in phosphate buffers (pH 7) gave a stable,water insoluable film on glassy carbon electrode surface.This poly(pyrogallol) film electrode was exploited for the selective preconcentration of Bi(Ⅲ)at a constant potential. The preconcentrated Bi(Ⅲ) was firstly reduced and then was determined by differential pulse anodic stripping voltammetry. Factors affecting the accumulation,reduction,stripping, and removal steps were investigated. Under optimized conditions,the calibration curve was linear in the range of 2.5×10 -9 to 6.5×10 -6 mol/L for Bi(Ⅲ) with a correlation coeffient of 0.9997(10 min accumulation).A detection limit of 1.4×10 -10 mol/L for Bi(Ⅲ)(S/N=3) was obtained for a 10 min accumulation. For eight successive determinations of 5×10 -8 mol/L Bi(Ⅲ), the relative standard deviation was 3 4%. The method was applied to determine Bi(Ⅲ) in real samples.