Accurate Analysis of Zr, Hf, Nb and Ta in High-Grade Metamorphic Rocks with ICP-MS
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摘要: 采用高压密闭溶样ICP-MS研究了片麻岩、榴辉岩等高级变质岩中Nb、Ta、Zr、Hf准确分析方法. 实验表明: 在温度为190℃时, 溶样时间大于36h, Nb、Ta、Zr、Hf可完全溶解, 而获得准确的分析结果. 但Nb、Ta在稀硝酸介质中的不稳定性会导致分析结果的误差, 采用0.1%HF介质的“F-基体”匹配, 可保持Nb、Ta长时间的稳定性. 所建立的高压密闭溶样ICP-MS分析方法用于苏鲁—大别地区片麻岩、榴辉岩等高级变质岩的分析, 经与XRF及碱熔融ICP-MS方法对比, 分析结果具有良好的一致性.
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关键词:
- 高级变质岩 /
- Nb、Ta、Zr、Hf /
- “F-基体”匹配 /
- 等离子体质谱分析
Abstract: This study indicates that to obtain the accurate contents of Zr and Hf in the high-grade metamorphic rocks (e.g., gneiss, granulite and eclogite) with ICP-MS, the rock-digesting time must be > 36 h at 190 ℃ in closed Teflon Bomb. Unlike Zr and Hf, the most important factor limiting the analytical precision and accuracy of Nb and Ta in ICP-MS analysis is their instability in the medium of diluted HNO3. Our technique of rock-digesting at 190 ℃ for 48 h in high-pressure sealed Teflon Bomb incorporating with "F- matrix" match effectively solve the problem of accurate analysis of Zr, Hf, Nb and Ta with ICP-MS.-
Key words:
- high-grade metamorphic rock /
- Nb /
- Ta /
- Zr and Hf "F- matrix" match
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图 2 溶样时间对Zr、Nb测定结果的影响
Fig. 2. Effects of digesting time on analysis results of Zr and Nb
表 1 实验研究样品情况
Table 1. Studied samples
表 2 ICP-MS仪器工作参数
Table 2. Operation parameters for ICP-MS
表 3 利用不同酸介质标准溶液对部分国际标样Zr、Hf、Nb、Ta直接测定结果与推荐值的比值
Table 3. Ratios of measured results to reference values for Zr, Hf, Nb and Ta of some international standards measured using different standard solutions with different acid conditions
表 4 采用不同溶样方法、条件及分析方法获得的Lu、Zr、Nb、Hf、Ta结果对比
Table 4. Comparison of Lu, Zr, Nb, Hf and Ta obtained by different sample-digestion and analytical methods
表 5 利用与XRF、碱熔融法ICP-MS分析结果对比
Table 5. Method evaluation by comparing the analytical results by different methods
表 6 方法检出限
Table 6. Limits of detection for the method
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