稀释硝酸微波消解辅助分析土壤中的5种元素

Assisted analysis capacity of diluted nitric acid with microwave-digestion for the 5 kinds of elements in soil

目的建立稀释硝酸溶液微波消解处理土壤样品的新方法。方法采用电感耦合等离子体质谱法(ICP-MS)测定了某城市10个不同乡村120份土壤样品中5种元素(Pb、Cd、Cr、As、Hg)的含量,并结合p H值进行污染程度评估。结果稀释硝酸的浓度为2.1 mol/L时可以替代常用的浓硝酸溶液,Cd、Hg、As、Pb和Cr的方法检出限分别为0.004 6μg/g、0.003 1μg/g、0.023μg/g、0.12μg/g和0.63μg/g,各元素的相关系数(r)>0.999 8,p H值整体分布不均匀,但是样品中元素含量具有同一变化规律:Hg<Cd<As<Pb<Cr,同时建立了土壤元素指纹图谱。其中J组大部分样品中Hg元素含量严重超标,实验样品大部分属于轻度污染。结论本方法具有成本低和无污染的特点,为土壤前处理方法的进一步研究提供了理论基础。

Objective To establish a new method for the determination of soil samples using diluted nitric acid solution and the microwave digestion. Methods The contents of 5 elements（ Cd,Hg,As,Pb,Cr） in 120 different soil samples from 10 countries in a city by inductively coupled plasma mass spectrometry（ ICP-MS）. Combined with the values of pH,the pollution degrees were assessed. Results When the concentration of diluted nitric acid solution was 2. 1 mol / L,the concentration mentioned above could replace the concentrated nitric acid. The detection limits of Cd,Hg,As,Pb,Cr were 0. 004 6 μg / g,0. 003 1 μg / g,0. 023 μg / g,0. 12 μg / g and 0. 63 μg / g,respectively. The correlation coefficient（ r） of those elements were greater than 0. 999 8. The distribution of the values of p H were not uniform,however,there was a regular pattern on the changes of the concentration of elements,which was Hg Cd As Pb Cr,and meanwhile,to set up a figureprinter spectrum for elements in soil samples. In addition,the concentration of Hg in the partly samples in team J overrode the standard values,with the most samples falling into slight contamination. Conclusion The characteristic of this method are lower cost and no pollution,and it provides a theoretical basis for the further study on the preteatment method of soil.