微波消解-电感耦合等离子体质谱法测定稻田土壤中的重金属

Determination of heavy metals in paddy soil by microwave digestion-inductively coupled plasma mass spectrometry

目的通过对微波消解中不同酸体系的筛选和相应多原子离子干扰的消除试验,建立稻田土壤中Cr、Ni、As、Cd、Pb、Hg的微波消解-电感耦合等离子体质谱(ICP-MS)测定方法。方法通过对硝酸、硝酸-氢氟酸、硝酸-氟硼酸3种不同酸体系消解效果的比较,分别采用硝酸-氢氟酸、硝酸-氟硼酸对稻田土壤样品进行消解,利用ICP-MS对样品中的Cr、Ni、As、Cd、Pb、Hg进行测定。以115In、185Re作为内标同位素,采用干扰校正方程和碰撞反应模式消除钨氧化物(WO+)等多原子离子干扰,标准曲线法定量。结果方法检出限为0.000 25 mg/kg^0.004 7 mg/kg,线性相关系数为0.999 8~1.000 0,土壤标准物质的测定结果均在标准值范围内,相对标准偏差为1.7%~6.1%。结论该方法操作简单,准确可靠,可满足稻田土壤样品中Cr、Ni、As、Cd、Pb、Hg的测定。

Objective To compare the different acid systems in microwave digestion and investigate the elimination test of polyatomic interferences,so as to develop a method for the determination of Cr,Ni,As,Cd,Pb,Hg in paddy soil by microwave digestion-inductively coupled plasma mass spectrometry（ ICP-MS）.Methods After comparing the efficiency of HNO3,HNO3-HF,HNO3-HBF4,the paddy soil samples were microwave-digested by HNO3-HF,HNO3-HBF4,respectively.Cr,Ni,As,Cd,Pb and Hg in the sample solution were determined with ICP-MS.With115 In and185Re as internal isotopes,correction equation and collision/reaction interface mode were used to eliminate the polyatomic interferences（ e.g.WO＋）.The quantification was based on standard curves.Results The detection limits of the method were within 0.000 25 mg/kg-0.004 7 mg/kg,with the correlation coefficient（ r） of 0.999 8-1.000 0.The results of certified reference material were within the reference values,with RSDs of 1.7%-6.1%.Conclusion The established method is simple,reliable and suitable for the determination of Cr,Ni,As,Cd,Pb and Hg in paddy soil.