样品的消解方法对定量分析重金属元素的影响

Effect of Digestion Methods on Quantitative Analysis of Heavy Metal Elements

为了研究不同消解方法对土壤样品中重金属元素测定的影响,分别采用电热板消解、高压罐密闭消解和微波消解3种方法对土壤标准样品(GBW07440)进行前处理;在电感耦合等离子体质谱(ICP-MS)优化条件下,测定了3种消解方法中5种重金属元素(Cr、Cu、Zn、Cd及Pb)含量,进而建立一种消解-ICP-MS检测土壤中重金属元素含量的最佳方法。结果表明:微波消解最彻底且消解液澄清,电热板和高压罐消解剩余残渣均较多;3种消解方法的检出限均能达到μg/L级或者更低,但是微波消解法的检出限最低。5种元素标准曲线线性关系较好(相关系数r>0.999 90),RSDmax(Cr、Cd、Pb)<RSDmax(Cu、Zn),仪器灵敏度、精准度较高,3种消解方法的测定值均能与参考值基本保持一致,方法准确可靠。综合比较认为,微波消解法更适于土壤中痕量重金属元素检测的前处理。

In order to investigate the effects of three digestion methods （platen heating digestion, high pressure closed-vessel digestion and microwave digestion） on analysis of Cr,Cu, Zn,Cd and Pb in the digestion,Cr,Cu,Zn,Cd and Pb in the digestons of the national standard reference mate-rial （GBW07440） digested respectively with three methods above were analyzed by ICP-MS under its optimized model to establish a best method for determining and analyzing a variety of heavy metals in soil. The results suggested that microwave digestion was a most complete method and its digestion solution was most clarifying, but the residue by platen heating digestion and pres-sure close-vessel digestion remained more than microwave digestion. Detection limits of three methods were up to level of μg/L or lower level. However, the level of microwave digestion was lowest. Correlative coefficient of the calibration curves was over 0. 999 90 by using ICP-MS deter- mination of five types of elements. Maximum RSD of Cr,Cd and Pb was lower than that of Cu and Zn. The sensitivity and accuracy of ICP-MS were satisfied. Basically, testing value of three rhethods brought into correspondence with standard value in certified reference material. In conclu-sion,the method of microwave digestion was more first recommended to digest soil heavy metals.