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测定了在不同浓度盐酸和硝酸介质中铁和镉于Dowex 1-X8阴离子交换树脂上的分配系数(Kd),试验表明:在0.5～4 mol/L的盐酸中,Kd(Cd2+)>103,即强吸附于阴离子交换树脂,而在0.1～1 mol/L的盐酸中,Kd(Fe3+)<10,即不吸附于树脂。由此确定了从大量铁中分离出镉的最优条件,并建立了ICP-AES测定不锈钢中微量镉元素的方法。在选定的仪器最佳工作条件下,测得样品加标回收率为94%～98%,相对标准偏差(n=7)<6%,方法重复性好、准确度高。
The partition coefficient (Kd) of iron and cadmium on Dowex 1-X8 anion exchange resin in different concentrations of hydrochloric acid and nitric acid was determined. The results showed that Kd (Cd2 +)> 103 in 0.5-4 mol / L hydrochloric acid Strong adsorption on the anion exchange resin, and in 0.1 ~ 1 mol / L of hydrochloric acid, Kd (Fe3 +) <10, that is not adsorbed on the resin. Thus, the optimal conditions for the separation of cadmium from a large amount of iron were determined and a method for the determination of trace cadmium in stainless steel by ICP-AES was established. Under the optimal working conditions of the selected instruments, the recoveries of spiked samples ranged from 94% to 98% with relative standard deviations (n = 7) <6%. The method has good repeatability and high accuracy.