金川铜镍硫化物样品中锇同位素比值的高精度分析
High-precise Determination of Osmium Isotopic Ratio in the Jinchuan Copper-Nickel Sulfide Ore Samples
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摘要: 采用两种独立的190Os稀释剂、4个不同的化学流程，用等离子体质谱仪、TRITON热表面电离质谱仪和MAT-262固体质谱仪3种质谱仪器，在4个实验室分别对采自金川铜镍硫化物样品的187Os/188Os同位素比值进行分析，样品分析数量达到56个。4个实验室获得的结果分别为0.3356±0.0018（n=12，2s）、0.3363±0.0008（n=6，2s）、0.3363±0.0010（n=18，2s）和0.3353±0.0034（n=20，2s）。采用ISOPLOT软件对所得56个数据进行加权平均计算，得到187Os/188Os同位素比值为0.33602±0.00022（置信度95%）。两台TRITON热表面电离质谱仪测量的结果几乎完全一致，且精度高于MAT-262固体质谱仪和等离子体质谱仪。比较了碱熔和Carius管两种溶样方法，结果表明，对于所研究的样品，用Carius管溶矿方式可以将含锇矿物完全溶解。Abstract: The ratio of 187Os/188Os determination in copper-nickel-sulfide ore samples from Jinchuan, China was carried out in 4 laboratories, including AIRIE of Colorado state university USA and other 3 Chinese laboratories, using 2 separate 190Os spikes and 4 different chemical processes. ICP-MS, TRITON and MAT-262 instruments were used for the measurements. 56 samples were determined with the results of 0.3356±0.0018（n=12, 2s）, 0.3363±0.0008（n=6, 2s）, 0.3363±0.0010（n=18, 2s） and 0.3353±0.0034（n=20,2s） from 4 different laboratories respectively. The weighted average value for 56 data was calculated using ISOPLOT software with result of 0.33602±0.00022 (confidence 95%). The results from two TRITON instruments are in good agreement with higher precision than those from ICP-MS and MAT-262 instruments. Two different digestion techniques (alkali fusion and Carius tube dissolution) were also compared. The results show that Carius tube acid digestion technique is feasible for completely digestion of all Os-bearing mineral phases and is suitable for 187Os/188Os ratio determination in copper-nickel-sulfide ore samples from Jinchuan, China.
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Key words:
- the /
- Jinchuan /
- copper-nickel-sulfide /
- ore
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