富铁含量土壤样品中痕量镉的测定

Determination of Trace Cd^(2+) in the Soil Samples of Rich IrOR Content

本文应用电位法,采用银基球型汞膜电极为指示电极,大面积银片电极为参比电极和883型极谱仪,阳极溶出法测定大量铁存在下的土壤样品中痕量镉。试样经酸分解,直接在pH=5.0的硫酸——醋酸钠介质中,选择适当的电解富集电位及阳极溶出电位进行扫描,选择适当的电极更新电位及更新时间,则得溶出峰电位为-0.5V,测定灵敏度高达5.0×10^(-10)g,相对误差小,效果良好。共存离子Fe^(3+)、Fe^(2+)、Al^(3+)、Zn^(2+)、Pb^(2+)、Cu^(2+)、PO_4^(3-)、Cl^-、NO_3^-等对镉的测定干扰不大。

By means of electric potential method and anodic stripping voltammetry, the trace Cd^(2+) in the soil samples of rich iron content can be determined by a 883—model polarograph, with the mercury membrane electrode of silver base sphericity as the indicating electrode and a large area of sheet—silver electrode as the reference electrode. The samples being resolved by acid, the peak point potential of the anodic stripping voltammetry and the sensitivity can be determined directly in the pH=5.0 H_2SO_4—NaAc medium by selecting the suitable electrolysis enriched potential and the anodie stripping voltammetry potential to scan, the suitble renewed electrode potential and oxidic renewed time. The peak point potential measured is -0.5V and the sensitivity as high as 5.0×10^(-10)g. The relative error is small and the effect is good. The coexistence ions Fe^(3+)、Fe^(2+)、Al^(3+)、Zn^(2+)、Pb^(2+)、Cu^(2+)、PO_4~^(3-)、 NO_3^- etc make little interference in the Cd^(2+) determination.