分别采用HNO3-HF、HNO3-HF-HCl和HNO3-HF-H2O2三种消解体系,通过微波和PTFE密封罐电热板对土壤标准物质进行前处理,采用电感耦合等离子体质谱(ICP-MS)对样品中的重金属元素Cr、Ni、Cu、Zn、As、Cd和Pb进行定量分析。探讨了前处理试剂(主要为HNO3、HCl和HF)以及土壤基体效应对Cr、Ni、Cu、Zn、As、Cd和Pb定量分析的影响。研究结果表明,前处理试剂对Cr、Ni、Cu、Zn、As、Cd和Pb的定量分析具有不同程度的影响;对于土壤基体,在三种消解体系下均可观察到基体抑制效应;采用PTFE密封罐电热板消解方法前处理,待测元素及相同元素不同同位素的方法空白和检出限均较低,效果整体优于微波消解法。特别是HNO3-HF-HCl消解体系,通过选用52Cr、60Ni、65Cu、66Zn、75As和206Pb等同位素,重金属元素Cr、Ni、Cu、Zn、As、Cd和Pb的测定值均能保证在标准值的允许误差范围内,可以满足大批量土壤样品中重金属元素同时定量分析的需要,为高效准确地开展土壤的风险评估以及为土壤的修复治理提供科学依据。
Three different systems including HNO3-HF,HNO3-HF-HCl and HNO3-HF-H2O2 were used to dissolve soil standard material of GBW 07405 with microwave and a PTFE sealed tank on electric heating plate respectively.The heavy metal elements of Cr,Ni,Cu,Zn,As,Cd and Pb in soil samples were quantitatively measured by Inductively Coupled Plasma-Mass Spectrometry(ICP-MS).Influence of the reagents,mainly HNO3,HCl and HF,for the digestion and matrix effect of the soil sample in the quantitative analysis of heavy metals of Cr,Ni,Cu,Zn,As,Cd and Pb are investigated in this paper.The results show that the reagents influence the quantitative analysis of Cr,Ni,Cu,Zn,As Cd and Pb to various extents and the depression effects caused by the soil matrix were observed for all the digestion systems.Digestion with the PTFE sealed tank on electric heating plate was prior to the microwave digestion as the blanks and the detection limits were lower for all the elements and the different isotopes of the same element.The results of Cr,Ni,Cu,Zn,As,Cd and Pb were especially consistent with the standard values within uncertainties for the digestion system of HNO3-HF-HCl for the chosen isotopes of 52Cr,60Ni,65Cu,66Zn,75As and 206Pb.This method meets the requirements of the quantitative analysis of the heavy metals Cr,Ni,Cu,Zn,As,Cd and Pb for large soil sample batches.This work can efficiently and accurately provide the scientific basis for risk assessment and maintenance for topsoil.