沉淀分离-密闭消解-电感耦合等离子体质谱法测定铬铁矿中铂族元素

Determination of platinum group elements in chromite by inductively coupled plasma-mass spectrometry with precipitation treatment and closed-digestion

建立了沉淀分离-密闭消解-电感耦合等离子体质谱法测定铬铁矿中铂族元素的新方法。采用硫磷混酸溶样(1:2,V/V),以硫酸肼为还原剂,实现了硫脲对包括Os在内的全部铂族元素的沉淀富集,沉淀经密闭溶样技术快速消解后接ICP-MS测定。试验中筛选出HBr来消除Os的记忆效应,并考察了Os在王水介质中的稳定性。结果表明:铂族6个元素的线性相关系数均在0.999以上,对标准物质GBW07292平行测定6次的相对标准偏差(RSD,n=6)在2.7%~8.4%之间,方法检出限(3σ)在0.055~0.21ng/g,采用国家一级标准物质GBW07201,GBW07202,GBW07292进行方法验证,测定值与认定值基本一致。

An analytical method was developed for determination of platinum group elements in chromite by inductively coupled plasma mass spectrometry （ICP-MS） with precipitation treatment and closed-digestion. The chromite sample was successfully digested using H2SO4 ＋ H3PO4 （V： V = 1：2 ）. Hydrazine sulfate was used as reducing agent to prevent the oxidation of Os when platinum group elements were precipitated with thiourea. Then, the precipitate was digested with closed-digestion using aqua regia. The memory effect of Os was eliminated by flushing through HBr and the stability of Os in aqua regia was also investigated. The study showed that ： the correlation coefficients of calibration curves of 6 platinum group elements were higher than 0. 999, RSD （ n = 6 ） of the analysis results of platinum group elements in standard reference material GBW07292 ranged from 2.7% - 8.4%, and the detection limits were 0. 055-0.21ng/g. The method was applied to the determination of platinum group elements in GBW07201, GBW07202 and GBW07292 with satisfactory results.