聚L-苏氨酸修饰电极方波溶出伏安法测定铅

在pH 3.5的NaAc-HAc缓冲液中,用循环伏安法制备聚L-苏氨酸修饰玻碳电极,探讨了Pb2+在修饰电极上的方波阳极溶出伏安特性,建立了方波阳极溶出伏安法测定Pb2+的方法。在最佳实验条件下,铅离子浓度在5.00×10-8~7.50×10-6 mol/L范围内与峰电流呈良好的线性关系,检出限为5.0×10-9 mol/L。测定2.50×10-6 mol/L Pb2+,当相对误差在±5%时,至少1 000倍K+、Na+、SO42-、PO43-、NO3-、Cl-、Ca2+、Ba2+、Mn2+、Mg2+、Al 3+、Zn2+、Fe3+、Cr3+、Co2+、Cd2+,200倍Cu2+不干扰Pb2+的测定。按照实验方法测定2个污水样中痕量铅,结果的相对标准偏差(RSD,n=6)分别为1.4%和2.4%,加标回收率分别为99%和103%。

Determination of lead by square wave stripping voltammetry with poly(L-threonine) modified electrode

The poly(L-threonine) modified glassy carbon electrode was prepared by cyclic voltammetry in NaAc-HAc buffer solution at pH 3.5. The square wave anodic stripping voltage current characteristics of Pb²⁺ on modified electrode were investigated. The determination method of Pb²⁺ by square wave anodic stripping voltammetry was established. Under the optimal experimental conditions, the concentration of Pb²⁺ in range of 5.00×10^-8- 7.50×10^-6 mol/L showed good linearity to the peak current. The detection limit was 5.0×10^-9 mol/L. The tolerant amount of co-existing ions for 2.50×10^-6 mol/L of Pb²⁺ was defined as resulting in error of ±5%, and was listed as following (in fold): K⁺, Na⁺, SO^2-₄, PO^3-₄, NO^-₃, Cl^-, Ca²⁺, Ba²⁺, Mn²⁺, Mg²⁺, Al³⁺, Zn²⁺, Fe³⁺, Cr³⁺, Co²⁺, Cd²⁺ (at least 1 000); Cu²⁺ (200). The content of trace lead in two waste water samples was determined according to the experimental method, and the relative standard deviation (RSD, n=6) of results was 1.4% and 2.4%, respectively. The recovery was 99% and 103%, respectively.