密闭消解-电感耦合等离子体质谱法测定铅矿石中痕量镓铟铊镉锗

Determination of trace gallium,indium,thallium,cadmium and germanium in lead ore by inductively coupled plasma mass spectrometry with closed digestion

铅矿床具有较高品位的各种稀散元素,因此准确测定铅矿石中Ga、In、Tl、Cd、Ge,对于矿产资源的节约、开发利用等具有重要意义。采用密闭消解方式处理样品,同时在消解过程中加入H_2SO_4(1+4)并水浴加热以沉淀分离Pb基体,分别选择^(69) Ga、^(115)In、^(205) Tl、^(114) Cd、^(72) Ge作为分析同位素,^(103) Rh为内标校正Ga、In、Cd、Ge,^(187) Re为内标校正Tl,实现了电感耦合等离子体质谱法对铅矿石中痕量稀散元素Ga、In、Tl、Cd、Ge的测定。实验表明,采用标准(STD)模式测定,Ga、Tl、Cd的背景等效浓度比动能歧视(KED)模式高出一个数量级,而In、Ge的背景等效浓度和KED接近,因此确定采用KED模式测定Ga、Tl、Cd,采用STD模式测定In、Ge;对KED模式下He气流速进行了优化,确定He气流速为5.8mL/min。方法线性方程的相关系数均不小于0.999 2,Ga、In、Tl、Cd、Ge的方法检出限分别为0.052 0、0.039 2、0.019 6、0.021 2、0.043 7μg/g。采用实验方法测定铅矿石实际样品中Ga、In、Tl、Cd、Ge,测得结果的相对标准偏差(RSD,n=6)为1.3%～5.0%,加标回收率为86%～112%。将实验方法应用于铅矿石标准物质中这5个元素的测定,所得结果与认定值吻合。

The lead deposit usually contained high-grade various scattered elements,so the accurate determination of Ga,In,Tl,Cd and Ge in lead ore has important significance to the saving,development and utilization of ore resources.The sample was digested in closed system.During the digestion process,H2SO4(1+4)was added to precipitate and separate Pb matrix under heating in water bath.69Ga,115In,205Tl,114Cd and72Ge were selected as the analytical isotopes.103Rh was used as internal standard to correct Ga,In,Cd and Ge,while187Re was used as internal standard to correct Tl.The determination of trace scattered elements in lead ore(i.e.,Ga,In,Tl,Cd and Ge)was realized by inductively coupled plasma mass spectrometry(ICP-MS).The results showed that the background equivalent concentrations of Ga,Tl and Cd at standard(STD)mode were one magnitude order higher than the kinetic energy discrimination(KED)mode,while the background equivalent concentrations of In and Ge at the above two modes were similar.Therefore,the KED mode was selected for determination of Ga,Tl and Cd,and STD mode was selected for determination of In and Ge.The flow rate of He gas at KED mode was optimized,and5.8mL/min was selected.The correlation coefficients of linear equations were not less than0.9992.The detection limit of Ga,In,Tl,Cd and Ge was0.0520,0.0392,0.0196,0.0212and0.0437μg/g,respectively.The proposed method was applied for determination of Ga,In,Tl,Cd and Ge in actual sample of lead ore.The relative standard deviations(RSD,n=6)of determination results were between1.3%and5.0%.The recoveries were between86%and112%.The contents of these five elements in certified reference material of lead ore were determined according to the experimental method,and the results were consistent with the certified values.