Environmental Measurement & Analysis Center, Environmental Infrastructure Research Department, National Institute of Environmental Research, Hwangyoun-ro 42, Seo-gu, Incheon, 22689, South Korea.
Department of Earth System Sciences, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul, 03722, South Korea.
Environ Monit Assess. 2019 Dec 13;192(1):41. doi: 10.1007/s10661-019-8017-8.
To evaluate the pretreatment processing for Cd isotope analysis of environmental samples, acid extractions and total digestions were examined with various environmental certified reference materials. Four certified reference material samples, including fly ash, polluted soil, domestic sludge, and industrial sludge, were digested by six different acid extraction and total digestion methods, and then Cd was separated to remove other matrix by anion-exchange column. The Cd recovery rates of the acid extraction methods were 2.6-89.1%, while those of the total digestion methods were 21.6-88.7%. In these results, the Cd recovery rates were dependent on the sample type. More than 80% of the Cd in the polluted soil and domestic sludge samples could be recovered regardless of the decomposition method, except one method. On the other hand, the Cd recovery rate from fly ash was low when total digestion was performed using a HF mixture, and the recovery rate by total digestion methods for industrial sludge was higher than that by acid extraction. In our results, Cd isotope ratios tended to be more positive by increasing the Cd recovery rates, suggesting that the light isotope of Cd was decomposed preferentially during the decomposition procedures. However, when more than 80% of the Cd in the samples was recovered, the Cd isotope ratios were determined to be similar. This indicated that at least 80% of the Cd should be recovered from environmental samples to accurately measure the Cd isotopic ratio of environmental samples.
为了评估环境样品 Cd 同位素分析的预处理过程，我们用各种环境认证标准物质检验了酸萃取和全消解两种方法。我们用六种不同的酸萃取和全消解方法对四种认证标准物质样品（飞灰、污染土壤、城市污泥和工业污泥）进行消解，然后用阴离子交换柱分离 Cd 以去除其他基质。酸萃取法的 Cd 回收率为 2.6%至 89.1%，而全消解法的 Cd 回收率为 21.6%至 88.7%。在这些结果中，Cd 的回收率取决于样品类型。除了一种方法之外，污染土壤和城市污泥样品中超过 80%的 Cd 可以用任何分解方法回收。另一方面，用 HF 混合物进行全消解时，飞灰中的 Cd 回收率较低，而工业污泥的全消解法 Cd 回收率高于酸萃取法。在我们的结果中，Cd 同位素比值随着 Cd 回收率的增加而趋于更正，这表明在分解过程中优先分解了 Cd 的轻同位素。然而，当样品中超过 80%的 Cd 被回收时，Cd 同位素比值则趋于相似。这表明，为了准确测量环境样品的 Cd 同位素比值，至少应从环境样品中回收 80%的 Cd。
