电感耦合等离子体质谱法测定地质样品中铜锌铕钆铽的干扰及校正

摘要

Since Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) detection is not in a closed vacuum system, ions generated from gas, water and acid may enter the detection system in the test procedures, resulting in interference, which affects accurate analysis for trace elements. Geological samples were decomposed by pressurized acid digestion of HF-HNO3, and Cu, Zn, Eu, Gd and Tb were simultaneously determined by ICP-MS. The instrument operating parameters were optimized and the interferences from the coexisting elements of Ti, Ba, Ce, Pr, Nd for the determination of Cu, Zn, Eu, Gd, Tb were studied. The interference correction of oxide interferences for the elements Ti, Ba, Ce, Pr and Nd was performed with interference coefficients by mathematical method, which improved the accuracy for Cu, Zn, Eu, Gd, Tb determination in geological samples. Interference coefficients of Cu, Zn, Eu, Gd and Tb were calibrated by determining similar concentrations of the interference elements Ti, Ba, Ce, Pr, Nd. The detection limits (10SD) for Cu, Zn, Eu, Gd and Tb were 0. 47, 0. 82, 0.002, 0. 004 and 0. 002 p,g/g, respectively. Both the accuracy and precision of the method were validated by analyzing standard reference materials GBW 07104, GBW 07105, GBW 07123, GBW 07303, GBW 07311, GBW 07402 and GBW07404 with RSD (ra = 12) less than5.0% and RE (n = 12) less than5.0%. The results were in good agreement with the certified values of the national standard materials of rock, soil and stream sediments. The method has been successfully used in practice for Cu, Zn, Eu, Gd and Tb determination in geological samples.%由于电感耦合等离子体质谱(ICP-MS)分析不是在封闭的真空系统中进行,在测定过程中,气体、水和酸产生的一些离子都可能进入检测系统,产生干扰,严重影响痕量元素的准确分析.文章采用氢氟酸-硝酸封闭压力酸溶分解样品,ICP-MS法同时测定地质样品中Cu、Zn、Eu、Gd、Tb,研究了Ti、Ba、Ce、Pr、Nd对Cu、Zn、Eu、Gd、Tb的干扰情况.实验选择质量数65Cu、66Zn、153Eu、157Gd、159Tb作为测定同位素,用干扰系数脱机校正法校正分别来自Ti、Ba、Ce、Pr、Nd的氧化物重叠干扰,有效地解决了被干扰元素在测定时数值准确度低的问题.方法检出限(稀释因子1000)为:Cu 0.47 μg/g、Zn 0.82μg/g、Eu 0.002 μg/g、Gd 0.004 μg/g、Tb 0.002 μg/g,方法精密度(RSD,n=12)＜5％,准确度(RE)＜5％.方法用岩石、土壤、水系沉积物国家一级标准物质进行验证,测定值与标准值相符,适用于地质样品中Cu、Zn、Eu、Gd、Tb的测定.