锍镍试金富集-电感耦合等离子体质谱法测定黑色页岩中的铂族元素

摘要

According to the characteristics of black shale with high abundants in C, S, Ni, Fe and Mo, the conventional reagent formula does not provide an ideal nickel sulphide button, which affects the accuracy of PGEs values. The improved reagent formula and optimized procedure of nickel sulphide fire assay have been developed for the determination of PGEs in black shale samples by Inductively Coupled Plasma-Mass Spectrometry ( ICP-MS ). The addition of Potassium nitrate as an oxidant of the fusion flux increases the recovery of PGEs by about 10%. After digestion by HC1, there was still a great amount of precipitations on the bottom of the beaker. This problem was resolved by adding a moderate amount of ferric chloride ( about 2-3 mL ) with a hot solution and stirring. The detection limits of the method for PGEs are 0. 054 ng/g for Ru, 0. 040 ng/g for Rh, 0.40 ng/g for Pd, 0. 032 ng/g for Ir, 0. 27 ng/g for Pt and 0. 026 ng/g for Os. The research results of different black shale samples are in good agreement with the reference values, showing that the method is reliable for determining the PGEs in black shale samples.%黑色页岩中碳、硫、镍等元素的含量很高,按照常规的锍镍试金熔剂配方不能形成较好的锍扣,影响铂族元素准确定值.本文通过调整试剂配方、优化操作流程等方式建立了黑色页岩中铂族元素的锍镍试金-电感耦合等离子体质谱(ICP-MS)测定方法.结果表明,加入适量硝酸钾可以将铂族元素回收率提高了大约10%.用盐酸溶解锍扣之后,溶液中仍然存在大量黑色沉淀,不易过滤和溶解,趁热在不断搅拌下加入2～3 mL三氯化铁溶液可以在很大程度上减少沉淀量,降低实验操作的难度和不确定性.方法检出限Ru为0.054 ng/g,Rh为0.040 ng/g,Pd为0.40 ng/g,Ir为0.032 ng/g,Pt为0.27 ng/g,Os为0.026 ng/g.精密度和准确度试验表明,该方法稳定可靠,可用于黑色页岩中铂族元素的准确测定.