丁二酮肟修饰玻碳电极差分脉冲溶出伏安法测定痕量铅

Determination of Trace Pb(Ⅱ)with Glassy Carbon Electrode Modified with Diacetyldioxime by Differential Pulse Stripping Voltammetry

提出了一种用丁二酮肟修饰玻碳电极,以差分脉冲溶出伏安法测定水中痕量铅离子的方法.在实验过程中,对各种实验参数如电解质种类及酸度、丁二酮肟用量、富集电位和时间、扫描速度等进行一定的优化.在pH=5.6的HAc-NaAc缓冲溶液中,铅离子与丁二酮肟生成螯合物富集在电极表面,然后在-0.8V被还原成零价的铅,在向阳极电位扫描的过程中,还原的铅被氧化而从电极表面溶出,于-0.60V形成阳极溶出峰,且峰电流与待测物浓度成正比,据此溶出峰电流可定量测定痕量铅离子.实验测得铅的线性范围为1×10-7mol/L至5×10-5mol/L,检测限为1×10-9mol/L.在同一含量的体系中平行测定6次1×10-7mol/LPb2+的溶液,其标准偏差为2.9%.用丁二酮肟修饰玻碳电极测定水样中的铅离子,取得满意结果.

In this paper,a diacetyldioxime modified glassy carbon electrode was developed for the determination of trace level of Pb2+ by differential pluse anodic strpping voltammetry.The experiment parameters,such as the type and acidity of electrolytes,amount of diacetyldioxime,accumulation potential and time,and scan rate were optimized.In pH5.6 HAc-NaAc buffer solution,Pb2+ was firstly perconcentrated on the surface of the modified electrode,and then reduced at-0.80V.In the following step,reduceded lead was stripped by applying voltammetric scanning.The peak current at-0.60V for Pb2+ was measured.It was found that the peak current is linear with the concentration in the range from 1×10-7mol/L to 5×10-5mol/L for Pb2+,and the detection limit is 1×10-9 mol/L.Its relative standard deviation obtained from 6 continuous determinations of the same solution containing 1.0×10-7mol/L Pb2+ was 2.9%.The applications for the detection of trace level of Pb2+ in water samples indicate that the result was favorable.