保证 Cd 的高回收率以及彻底的 Sn 干扰去除是获得精确镉同位素组成的前提,目前报道的多种 Cd 分离与纯化方法获得的 Cd回收率有较大差异(42. 6% ~ 99. 8% ),且去除 Sn 干扰的效果也不同(去除率在 87. 8% ~ 97. 4% 之间),Cd 回收率和 Sn 去除率均不理想.本文对前人报道的分离方法进行对比实验,发现 0. 1 mol/ L氢溴酸 - 0. 5 mol/ L 硝酸是分离 Cd 和 Sn 的有效试剂,增加该组混合酸的用量可淋洗出样品中更多的 Sn 且不会损失 Cd,当混合酸的淋洗用量增加至 30 mL 时,Sn 的淋洗率达到99. 8% 以上,Cd 的回收率亦达到 99. 0% ± 0. 5% ,可满足土壤样品镉同位素的测定要求.本工作为获得高精度的镉同位素组成奠定了基础,为研究土壤环境中镉的污染来源提供了技术手段.%In order to determine Cd isotopic composition accurately,the key is to guarantee Cd recovery and reduce Sn interference. The recoveries of Cd with various separation and purification methods reported by previous studies show a large range variation from 42. 6% to 99. 8% ,and the removal efficiency of Sn interference are various (87. 8% - 97. 4% ). Both the Cd recovery and Sn removal are not ideal. Reported in this study,0. 1 mol/ L HBr-0. 5 mol/ L HNO3 mixture was determined to be a more effective solution to separate Cd from Sn. By increasing the amount of this mixture during leaching,more Sn can be removed from the samples without Cd loss. When 30 mL of mixture is used during leaching,more than 99. 8% Sn can be leached out from the sample and the Cd recovery is 99. 0% ± 0. 5% . This method can be utilized for Cd isotope analyses of soil samples,offering new insight for high-precision Cd isotope measurement and serving as a technical method for Cd pollution tracing in the study of environmental soil.
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