镉(Ⅱ)-7-(4-氯-2-硝基苯偶氮)-8-羟基喹啉-5-磺酸体系的吸附伏安法研究

Adsorptive Stripping Voltammetry of Cadmium(Ⅱ)-7-(4-Chloro-2-nitrophenylazo)-8-Hydroxy-quinoline-5-sulfonic Acid System

本文报道了一种测定痕量镉离子的灵敏的电分析方法。在pH8.34 NH_3-NH_4Cl介质中,CNAQS-Cd^(2+)络合物在-0.72V有一灵敏的吸附还原峰,峰电流与镉浓度在一定范围内成线性关系,最低检测限为0.20ng/ml。确定Cd^(2+)-CNAQS的络合比为1:1,并对其电化学机理进行了初步的探讨,拟定了测定痕量镉的方法,应用于高炉煤气洗涤污水中镉分析,结果与原子吸收法一致。

A sensitive adsorptive stripping voltammetric determination of trace cadmium was reported. In NH_3-NH_4Cl medium (pH 8.34), the complex of cadmium with 7-(4-chloro-2-nitrophenylazo)-8-hydroxy-quinoline-5-sulfonic acid (CNAQS) can produce a sensitive adsorptive reduction peak at -0.72 V (vs. SCE) by differential pulse voltammetry. The detection limit and the linear range of the method were 0.20ng/ml and 2～90 ng/ml, respectively. The ratio of cadmium to CNAQS in the complex was found to be 1:1, the adsorptive voltammetric characteristics of the complex was studied. The method has been applied to the determination of cadmium in polluted water of gas-washing in blast furnace, and the results conform to those obtained by atomic absorption spectrometry.