碱熔-强酸型阳离子交换树脂分离-电感耦合等离子体质谱法测定地质样品中硼锗钼锡碘钨

B、Ge、Mo、Sn、I和W是区域地质调查样品54种元素必测项目,目前对这6种元素的测定广泛使用的方法基本是单独或两项结合进行样品的制备和测定,分析效率较低。实验建立了Na₂O₂熔融样品,强酸型阳离子树脂交换分离高含量钠盐,电感耦合等离子体质谱法(ICP-MS)同时测定地质样品中B、Ge、Mo、Sn、I和W的方法。通过试验确定了对于0.5000g地质样品,以3.0g Na₂O₂为熔剂于750℃熔融8min,样品可熔解完全;对于引入的钠盐,通过对待测溶液使用强酸型阳离子交换树脂动态交换振荡30min可消除Na⁺对待测元素的影响;且测试时在每2个待测液之间以0.5%(V/V)氨水作清洗液可降低B、I的记忆效应。采用校正方程在线校正了⁷⁴Ge的同量异位素干扰;选用碰撞模式测定Mo和W,消除多原子离子干扰;B、Ge、Sn和I选用普通模式测定。结果表明,在优化的条件下,B、Ge、Mo、Sn、I和W的检出限在0.092~0.57μg/g之间。按照实验方法对土壤成分分析标准物质GBW07451和水系沉积物成分分析标准物质GBW07362中B、Ge、Mo、Sn、I和W进行测定,相对误差和相对标准偏差均满足DZ/T 0258—2014《多目标区域地球化学调查规范》的要求。优化后的方法用于实际地质样品的分析,测定值与经典方法的结果一致,实现了B、Ge、Mo、Sn、I和W的同时测定,提高了测试效率。

Determination of boron,germanium, molybdenum,tin, iodine and tungsten in geological samples by alkaline fusion-strong acid cation exchange resin separation-inductively coupled plasma mass spectrometry

B, Ge, Mo, Sn, I and W belong to necessary testing items of 54 elements in geochemical samples. At present, the efficiency of the widely used method for the sample preparation and determination by single or combination is low. The sample was fused with Na₂O₂ followed by separation of high content sodium salt using strong acid cation exchange resin. A method for the simultaneous determination of B, Ge, Mo, Sn, I and W in geological samples by inductively coupled plasma mass spectrometry (ICP-MS) was established. In experiments, 0.5000g of geological sample could be completely fused with 3.0g of Na₂O₂ at 750℃ for 8min. For the introduced sodium salt, the effect of Na⁺ on the determination could be eliminated when the testing solution was treated by strong acid cation exchange resin for dynamic exchange oscillation for 30min. In addition, the memory effect of B and I could be reduced by using 0.5%(V/V) ammonia as the cleaning solution between each two testing samples. The isobaric interference of ⁷⁴Ge was online corrected using calibration equation. Mo and W were determined in collision mode to eliminate the interference of polyatomic ions, while B, Ge, Sn and I were measured in normal mode. The results showed that under the optimized conditions, the limit of detection for B, Ge, Mo, Sn, I and W was between 0.092μg/g and 0.57μg/g, respectively. The contents of B, Ge, Mo, Sn, I and W in certified reference materials of soil (GBW07451) and stream sediment (GBW07362) were determined according to the experimental method. The relative error and relative standard deviation could meet the requirements of DZ/T 0258-2014 . The optimized method was applied to the analysis of actual geological samples, and the found results were consistent with those obtained by classical methods, which realized the simultaneous determination of B, Ge, Mo, Sn, I and W. Moreover, the testing efficiency was greatly improved.