土壤中金属元素分析的无人值守消解方法研究

Study on Unattended Digestion Method in Analyzing Heavy Metal Content in Soil

传统土壤消解的赶酸操作需要长时间人工值守,增加了健康风险和操作误差,且不能完全除去前期酸液。本文将赶酸时蒸发近干改进为蒸发至干,再对蒸干残渣再次消解。仅使用浓硝酸溶解残渣效果不佳(RSD为0. 25%～13%,回收率为84%～112%)。还需对残渣再次微波消解(RSD为0. 42%～2. 7%,回收率为94%～106%),以实现无人值守,并除去操作误差和简化定容操作。对于敞口消解可选用浓硝酸加热消解残渣(RSD为0. 22%～5. 3%,回收率为87%～110%),但改进收益不如微波消解法。

The traditional acid removal operation of soil digestion requires a long time of manual duty,which increases health risks and operational errors,and can not completely remove the pre-acid solution.The neat-drying acid-driving operation in traditional digestion method was changed to completely evaporate to dry.And then the dry residue was dissolved again.The experimental results showed that the effect was poor when only using concentrated nitric acid to completely dissolve the residue(RSD was 0.25%~13%,recovery was 84%~112%).The residue needed to be dissolved by microwave digestion(RSD was 0.42%~2.7%,recovery was 94%~106%).Meanwhile,it could bring the advantages of unattended process,removal of operating error,and simplified operation of fixed volume.For open-digestion,concentrated nitric acid could be chosen to heat the residue(RSD was 0.22%~5.3%,recovery was 87%~110%).But the benefits were not as good as microwave digestion.