Single-step separation scheme and high-precision isotopic ratios analysis of Sr–Nd–Hf in silicate materials
Single-step separation scheme and high-precision isotopic ratios analysis of Sr–Nd–Hf in silicate materials
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DOI：
10.1039/c3ja50384d
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发表时间：
2014-07
影响因子：
3.4
通讯作者：
Chaofeng Li;Jing-hui Guo;Yue-heng Yang;Zhuyin Chu;Xuan‐Ce Wang
中科院分区：
文献类型：
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作者：
Chaofeng Li;Jing-hui Guo;Yue-heng Yang;Zhuyin Chu;Xuan‐Ce Wang
热电离质谱和多接收器电感耦合等离子体质谱被认为是测定地质样品中 Sr-Nd 和 Hf 同位素比的“金标准”，因为这些方法具有极高的精密度和准确度。然而，耗时且繁琐的化学程序阻碍了样品通量。传统上采用三步离子交换树脂分离法从基质元素中纯化 Sr-Nd-Hf。在这项研究中，开发了一种一步式 Sr-Nd-Hf 分离方案来处理地质样品。该分离方案基于传统 AG50W-X12 阳离子交换树脂和 LN Spec 萃取色谱材料的组合使用，无需任何中间蒸发步骤。该方案不仅可以防止使用多级离子交换树脂操作过程中的交叉污染，还可以显着提高样品制备的效率。我们的化学程序的稳定性通过对六种国际硅酸盐岩石参考材料中 87Sr/86Sr、143Nd/144Nd 和 176Hf/177Hf 比率的重复测量得到证明。这些标准岩石获得的分析结果与已发表的数据非常吻合。 BCR-2 标准样品的外部再现性（2 SD，n = 10）对于 87Sr/86Sr 为 ±0.000018，对于 143Nd/144Nd 为 ±0.000010，对于 176Hf/177Hf 为 ±0.000014。
Thermal ionization mass spectrometry and multiple-collector inductively coupled plasma mass spectrometry are considered to be “gold standards” for the determination of the isotope ratios of Sr–Nd and Hf in geological samples because of the extremely high precision and accuracy of these methods. However, the sample throughputs are hindered by time-consuming and tedious chemical procedures. Three-step ion exchange resin separation is traditionally employed to purify Sr–Nd–Hf from matrix elements. In this study, a one-step Sr–Nd–Hf separation scheme was developed to process geological samples. The separation scheme is based on the combined use of conventional AG50W-X12 cation-exchange resin and LN Spec extraction chromatographic material without any intervening evaporation step. The protocol not only prevents cross-contamination during operation using multiple-stage ion exchange resins but also significantly improves the efficiency of sample preparation. The stability of our chemical procedure was demonstrated by replicate measurements of 87Sr/86Sr, 143Nd/144Nd, and 176Hf/177Hf ratios in six international reference materials of silicate rocks. The analytical results obtained for these standard rocks compare well with the published data. The external reproducibility (2 SD, n = 10) of a BCR-2 standard sample was ±0.000018 for 87Sr/86Sr, ±0.000010 for 143Nd/144Nd, and ±0.000014 for 176Hf/177Hf.