Cd(Ⅱ)-N-邻甲苯基-N'-(氨基对苯磺酸钠)硫脲—吡啶体系中镉的极谱测定

Polarographic Determination of Cadmium in Cd(Ⅱ)-N-o-Tolyl-N’-(sodim-p-aminobenzenesulfonate)thiourea and Pyrridine System

在含有0.5%吡啶的 NH_3-NH_4Cl 缓冲溶液(pH9.8)中,镉与新合成的试剂 N-(邻甲苯基)-N-(氨基对苯磺酸钠)硫脲于-0.72V(vs.SCE)产生灵敏的还原峰。峰电流与 Cd(Ⅱ)浓度在10～800ng/ml 范围内有良好的线性关系,检测限为5ng/ml,直接测定高纯锌及锌盐中痕量镉,得到了满意结果。本文对新试剂和吡啶增加测定镉的灵敏度的原因及电极反应机理进行了研究。

In NH_3-NH_4Cl buffer solution(pH 9.8)containing 0.5% pyridine,a sensitive reductive wave of Cd(Ⅱ)-N- o-tolyl-N'-(sodium-p-aminobenzenesulfonate)thiourea(TABST)is obtained at -0.72V(vs.SCE).The peak current is proportional to the concentration of Cd(Ⅱ)in the range 10-800ng/ml.The detection limit for Cd(Ⅱ)is 5 ng/ml.This method has been applied to the determination of cadmium in pure zinc and zinc acetae with satisfactory results.The mechanism of electrode reaction and the reasons that TABST and pyridine enhances the sensitivity of determination cadmium are also studied.