High-precision copper and iron isotope analysis of igneous rock standards by MC-ICP-MS
High-precision copper and iron isotope analysis of igneous rock standards by MC-ICP-MS
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利用 MC-ICP-MS 对火成岩标准品进行高精度铜和铁同位素分析
DOI：
10.1039/c3ja50232e
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发表时间：
2014-01-01
影响因子：
3.4
通讯作者：
Lu, Yinghuai
中科院分区：
文献类型：
--
作者：
Liu, Sheng-Ao;Li, Dandan;Lu, Yinghuai
Cu和Fe的稳定同位素系统是地质和生物过程的重要示踪剂。一般来说，铜和铁从基体中分离是通过两种独立的、完全不同的方法实现的。在这项研究中，我们报告了一种利用强阴离子树脂AG-MP-1M从火成岩基质中一步阴离子交换分离铜和铁的方法。采用多收集器电感耦合等离子体质谱法（Neptune plus）测量了铜和铁的同位素比值。一些样品的铜同位素测量也采用了用Zn进行外部归一化校正仪器偏差的方法。此外，还对所有可能影响同位素测量精度的参数进行了检验。长期外重复性优于δ65Cu的±0.05‰（2SD）和δ56Fe的±0.049‰（2SD）。利用该方法测定了玄武岩、辉绿岩、角闪岩、安山岩和花岗闪长岩等商业火成岩标准的铜、铁同位素组成。火成岩标准的δ65Cu值变化范围为- 0.01 ~ +0.39‰（n = 11），总体变化范围为0.40‰，超过目前分析精度的8倍左右。稳定铜同位素分析精度的提高表明，火成岩的铜同位素组成并不均匀。一步分离Cu和Fe的方法以及高精度的Cu和Fe同位素比值分析对于经济高效地研究地质和生物领域稳定的Cu和Fe同位素系统具有重要的优势。
Stable isotopic systematics of Cu and Fe are two important tracers for geological and biological processes. Generally, separation of Cu and Fe from a matrix was achieved by two independent, completely different methods. In this study, we report a method for one-step anion-exchange separation of Cu and Fe from a matrix for igneous rocks using strong anion resin AG-MP-1M. Cu and Fe isotopic ratios were measured by multi-collector inductively coupled plasma mass-spectrometry (Neptune plus) using a sample–standard bracketing method. External normalization using Zn to correct for instrumental bias was also adopted for Cu isotopic measurement of some samples. In addition, all parameters that could affect the accuracy and precision of isotopic measurements were examined. Long-term external reproducibility better than ±0.05‰ (2SD) for δ65Cu and ±0.049‰ (2SD) for δ56Fe was routinely obtained. Cu and Fe isotopic compositions of commercially accessible igneous rock standards including basalt, diabase, amphibolite, andesite and granodiorite were measured using this method. δ65Cu values of igneous rock standards vary from −0.01 to +0.39‰ (n = 11) with an overall range (0.40‰) that exceeds about 8 times that of the current analytical precision. The improved precisions of stable Cu isotopic analysis thus demonstrate that igneous rocks are not homogeneous in Cu isotopic composition. The procedure for one-step separation of Cu and Fe and high-precision analysis of Cu and Fe isotopic ratios have an important advantage for economical and efficient study of stable Cu and Fe isotopic systematics in geological and biological fields.