溶样方法对电感耦合等离子体质谱法测定区域地球化学调查样品中6种元素的影响

Influence of sample dissolution method on the determination of six elements in regional geochemical survey sample by inductively coupled plasma mass spectrometry

针对区域地球化学调查样品,采用HCl-HNO_3-HClO_4-HF消解样品、王水提取技术,以^(59)Co、^(60)Ni、^(65)Cu、^(66)Zn、^(114)Cd、^(208)Pb作为测定同位素,采用间接经验公式校正质谱干扰,最终实现了电感耦合等离子体质谱法(ICP-MS)同时对Co、Ni、Cu、Zn、Cd和Pb等6种微量元素的测定。详细对比分析了HCl-HNO_3-HClO_4-HF消解法、王水消解法、微波消解法3种试样处理方法对土壤、水系沉积物和岩石成分分析标准物质的分析数据,结果表明,HCl-HNO_3-HClO_4-HF消解法和微波消解法的测定值与认定值相符;因微波消解法一次性处理样品数量有限,不适合大批量地质样品分析,故实验选取HCl-HNO_3-HClO_4-HF法对样品进行溶样。Co、Ni、Cu、Zn、Cd和Pb的校准曲线相关系数均达0.999 9以上,方法检出限(μg/g)分别为:Co 0.04,Ni 0.69,Cu 0.89,Zn 1.31,Cd 0.029,Pb 0.34。将方法应用于土壤、水系沉积物和岩石成分分析标准物质中6种金属元素的测定,结果与认定值基本一致,相对标准偏差(RSD,n=12)均小于8%。方法应用于实际区域地球化学调查样品分析,结果与X射线荧光光谱法(XRF)相吻合。

The regional geochemical survey sample was dissolved with HCl- HNO3-HClO4-HF . After extraction by aqua regia, the content of six microelements （including Co , Ni , Cu , Zn , Cd and Pb ） was determined by inductively coupled plasma mass spectrometry （ICP-MS ） using ^59Co , ^60Ni , ^65Cu , ^66Zn , ^114Cd and ^208Pb as determination isotopes. The mass spectrometry interference was corrected by indirect empiri-cal formula. Three sample dissolution methods （i . e. , HCl- HNO3-HClO4-HF digestion method, aqua regia digestion method and microwave digestion method） were compared. The determination data of certified reference materials of soil, stream sediment and rock were analyzed. The results indicated that the determination results of HCl- HNO3-HClO4-HF digestion and microwave digestion were consistent with the certified values. The treatment amount of sample in microwave digestion method was little, which was not suitable for the analysis of bulk geological samples. Therefore, the samples were dissolved with HCl- HNO3-HClO4-HF digestion method in this study. The correlation coefficients of calibration curves of Co , Ni,Cu, Zn,Cd and Pb were higher than 0. 999 9. The detection limit of method （μg /g） was Co 0. 04, Ni 0. 69 , Cu 0. 89 , Zn 1. 31, Cd 0. 029 and Pb 0. 34, respectively. The proposed method was applied to the determination of six metal elements in standard sample of soil, stream sediment and rock for composition analysis. The found results were basically consistent with the certified values. The relative standard deviations （RSD , n = 12） were less than 8 %. The method was also used in the analysis of actual regional geochemical survey samples, and the results were consistent with those obtained by X-ray fluorescence spectrometry （XRF ）.