Determination of low concentrations of platinum group elements in geological samples by ID-ICP-MS
Determination of low concentrations of platinum group elements in geological samples by ID-ICP-MS
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DOI：
10.1039/b400742e
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发表时间：
2004-10
影响因子：
3.4
通讯作者：
L. Qi;Mei‐Fu Zhou;C. Wang
中科院分区：
文献类型：
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作者：
L. Qi;Mei‐Fu Zhou;C. Wang
准确和精确地测定地质样品中ppb浓度的铂族元素（PGEs）是重要的，但存在问题。本文报道了一种改进的同位素稀释-电感耦合等离子体质谱法（ID-ICP-MS）测定亚ppb水平Pt、Pd、Ru、Ir和Rh的分析方法。在实验之前，所有的试剂都经过仔细的纯化：HBO3、HCl和SnCl2用共沉淀法纯化，HNO3和HF用亚沸蒸馏法纯化。用HF、HNO3和HCl对10克样品进行分解。用H3BO3络合可使酸消化产生的氟化物残留量最小化，因此可以在刚玉坩埚中进行过氧化钠的小熔合，而不是大量的Na2O2熔合，以降低空白水平。将酸消解溶液和Na2O2融合溶液结合，通过共沉淀法对PGEs进行预浓缩。Cu、Ni、Zr和Hf采用阳离子交换树脂和P507萃取层析树脂组合在同一柱中去除，以减少它们的干扰。Pt, Pd， Ru和Ir采用ID-ICP-MS测定，而单同位素元素Rh采用高富集的194Pt作为内标，通过外部校准测定。富集的194Pt尖峰在Te沉淀过程中表现出与Rh相似的行为，是理想的内标。PGE的测定限为0.01 ~ 0.19 ng g−1。该方法对CCRMP （CANMET, Ottawa, Canada）认证标准物质WGB-1（辉长岩）、TDB-1（辉绿岩）和UMT-1（超镁铁尾矿）的测定结果与报告值吻合较好，但当Ru、Rh和Ir浓度低于0.5 ng g−1时，与认证值存在差异。
Accurate and precise determination of platinum group elements (PGEs) at ppb concentrations in geological samples is important but problematic. This paper reports an improved analytical method for the determination of Pt, Pd, Ru, Ir and Rh at sub-ppb levels by isotope dilution-inductively coupled plasma mass spectrometry (ID-ICP-MS). Prior to experimentation, all reagents were carfully purified: HBO3, HCl and SnCl2 by Te coprecipitation and HNO3 and HF by subboiling distillation. HF, HNO3 and HCl were used to decompose 10 gram sample. The fluoride residue from the acid digestion is minimized by using H3BO3 for complexation, thus mini-fusion of sodium peroxide can be performed in corundum crucibles instead of bulk Na2O2 fusion to lower blank level. The solution of acid digestion and Na2O2 fusion are combined and PGEs are then pre-concentrated by Te coprecipitation. Cu, Ni, Zr and Hf are removed using cation exchange resin and P507 extraction chromatography resin combined in the same column to minimize their interference. Pt, Pd, Ru and Ir are determined using ID-ICP-MS, whereas the mono-isotopic element, Rh, is determined by external calibration using highly enriched 194Pt as the internal standard. The enriched 194Pt spike behaves similar to Rh during the Te precipitation procedure and acts as an ideal internal standard. The determination limits for PGE range from 0.01–0.19 ng g−1. The results obtained using this new method for the CCRMP (CANMET, Ottawa, Canada) certified reference materials WGB-1 (gabbro), TDB-1 (diabase) and UMT-1 (ultramafic ore tailings), show good agreement with the reported values, but have discrepancies compared with the certified values when the concentration of Ru, Rh and Ir below 0.5 ng g−1.