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有读书笔记Directly determining 143Nd/144Nd isotope ratios using thermal ionization mass spectrometry for geological samples without separation of Sm–Nd

唐唐 添加于 2011-11-24 05:59 | 2314 次阅读 | 0 个评论

  •  作 者

    Li C-feng, Li X-hua, Li Q-li, Guo J-hui, Li X-hui

  •  摘 要

    Sm–Nd isotopic system is a powerful tracer and dating tool in geochemistry and cosmochemistry. Thermal ionization mass spectrometry (TIMS) is the benchmark method for obtaining high precision Nd isotope ratios. Traditionally, a two-step separation was employed in order to obtain high purity Nd fraction, which makes the sample preparation time-consuming. In this study, we present a new method to directly obtain precise and accurate Nd isotope ratios of geological samples without Sm–Nd separation. The key point is to well correct isobaric interferences of 144Sm on 144Nd for this method. The accurate intensity of 144Sm can be obtained using 147Sm/144Sm ratio of 4.87090 and mass discrimination factor of Sm (βSm), which is achieved using 147Sm/149Sm ratio of 1.08583 with Russell equation. Consequently, the real intensity of 144Nd was achieved, then also raw 146Nd/144Nd, 143Nd/144Nd ratios. Finally, 143Nd/144Nd ratio is normalized using 146Nd/144Nd ratio of 0.7219 following exponential law. The accuracy of this method is validated by replicating TIMS measurements for thirteen international reference materials of silicate rock, spanning a wide range of Sm/Nd from 0.13 to 0.46 and bulk compositions. The measured 143Nd/144Nd ratios of the rock standards are in good agreement with the reported values of within error of ±0.004%. Our new method shortens the analytical procedure and significantly improves sample throughput which greatly contributes to those studies requiring a large dataset and quick analysis.

  •  详细资料

    • 文献种类: Journal Article
    • 期刊名称: Journal of Analytical Atomic Spectrometry
    • 期刊缩写: J. Anal. At. Spectrom.
    • 期卷页: 2011年  第26卷 第10期 2012页
    • ISBN: 0267-9477

  • 学科领域 自然科学 » 地球科学

  • 相关链接 DOI URL 

  •  唐唐 的文献笔记  订阅

    研究建立测定稀土钕同位素比值新方法

    直接测试国际岩石标样稀土中143Nd/144Nd比值和传统方法的类比
     
    钕同位素在同位素地球化学与地质年代学研究中具有重要的应用价值。为准确获得 143Nd/144Nd同位素比值，传统方法需要通过两阶段离子交换技术分离出纯净的钕，再采用热电离质谱仪（TIMS）或多接收电感耦合等离子体质谱仪 （MC-ICP-MS）进行测试。首先，将溶解后的样品溶液通过阳离子交换柱（AG50W-X8/12）去除基体，同时回收稀土元素（REEs）。然后， 采用萃淋树脂交换柱（P507/204 or LN）分离出纯净的Nd，再进行测试。近年来，采用MC-ICP-MS已实现了直接测定稀土中的Nd同位素比值。然而，对于钕同位素最主要的分析仪器 TIMS，至今未实现该技术的建立，其中如何准确扣除144Sm干扰是该技术的主要难点。
     
    中科院地质与地球物理研究所固体同位素实验室李潮峰高级工程师及其合作者利用Triton TIMS质谱仪进行了该方法的研制，建立了有效的扣除方法。系列混和标准溶液和岩石标样的测定结果表明：通过阳离子交换柱分离出的REEs溶液，无需 Sm-Nd分离，热电离质谱仪同样可以获得准确的143Nd/144Nd同位素比值，减少了化学分离纯化步骤，提高了一倍的制备效率。
     
    该研究成果近期发表在国际知名的分析化学期刊《分析原子光谱学期刊》（Journal of Analytical Atomic Spectrometry） 上（Li et al. Directly determining 143Nd/144Nd isotope ratios using thermal ionization mass spectrometry for geological samples without separation of Sm-Nd. Journal of Analytical Atomic Spectrometry. 2011, 26（10）: 2012–2022）。（来源：中国科学院地质与地球物理研究所）
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