毛细管电泳单脉冲伏安测定重金属铜铅锌镉

Determination of Copper,Zinc,Lead and Cadmium by Capillary Electrophoresis with Single Pulse Voltammetric Detection

以毛细管为分离通道 ,在KNO3 缓冲溶液中 ,用表面镀汞膜的金微电极作为工作电极 ,采用单脉冲伏安法同时测定铜、锌、铅、镉含量 ,考察并优化了影响分离和检测的相关因素 :缓冲溶液pH、分离高压、脉冲上限和下限、脉冲宽度等。该法的最佳实验条件 :5mmol/LKNO3(pH6.0) ,分离高压20kV ,脉冲上限 -0.2V ,脉冲下限 -1.15V(vs.SCE) ,脉冲宽度500ms。结果表明 ,各峰面积与其离子浓度成线性关系 ,线性范围(μg/mL)分别为 :铜5.0×10-2～10.0;锌1.0×10-2～10.0 ;铅5.0×10-2～5.0 ;镉2.0×10-2～10.0。加标回收率在95%～110%之间。

Amethod forthe separation and simultaneous determination of Cu 2+ ,Zn 2+ ,Pb 2+ and Cd 2+ in aqueˉous media bycapillaryelectrophoresis withsingle pulse voltammetric detectionhas been investigated.The workˉing electrode is a mercury-coated gold microelectrode with a diameter of100μm.The oxidation and deoxidaˉtion of the ions would take place,when an appropriate potential was applied on the working electrode in elecˉtrolytes.The effects of pH,high voltage for separation,high and lowpulse potentials and pulse intervals on the working electrodes were studied and optimized.Under favorable conditions:5mmol/L potassium nitrate buffer solution at pH6.0;separation potential,20kV;high and low pulse potential,0.20and-1.15V(vs.SCE)and pulse interval,500ms;the separation of the four ions in standard samples were observed in20min.The relationships between the concentrations and the peak areas for Cu 2+ ,Zn 2+ ,Pb 2+ and Cd 2+ were linˉear over the ranges5.0×10 -2 ～10.0μg/mL,1.0×10 -2 ～10.0μg/mL,5.0×10 -2 ～5.0μg/mL and2.0×10 -2 ～10.0μg/mL,respectively.The detection limits(S/N=3)were4×10 -2 ,8×10 -3 ,2×10 -2 and1×10 -2 μg/mL,respectively.The recoveries ranged from95%to110%.The technique was succesˉsively applied for the rapid and simultaneous determination of copper,zinc,lead and cadmium in water samples.