New sample preparation techniques for the determination of Si isotopic compositions using MC-ICPMS
New sample preparation techniques for the determination of Si isotopic compositions using MC-ICPMS
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DOI：
10.1016/j.chemgeo.2006.06.006
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发表时间：
2006-11-30
期刊：
影响因子：
3.9
通讯作者：
Halliday, A. N.
中科院分区：
文献类型：
--
作者：
Georg, R. B.;Reynolds, B. C.;Halliday, A. N.
用于测定其天然稳定同位素组成的Si的纯化技术在过去一直基于对气源质谱的要求，而不是MC-ICPMS。为了用MC-ICPMS进行高精度分析，必须有非常纯的溶液，本文提出了一种从天然样品中分离和纯化Si的新技术，以改进同位素比的测定。一种方法已被优化的基础上，碱性融合，然后通过离子交换色谱。自然样品，如河水样品和硅酸盐矿物/岩石样品的应用。碱熔法避免了氢氟酸（HF）的使用，氢氟酸（HF）的使用给使用MC-ICPMS测定Si同位素比值带来了困难。通过消除HF，实现了灵敏度增加30-40%，以及质量偏差稳定性的显著增强，导致再现性提高2倍。阳离子交换法能够处理非常小的样品（3.6 μ g Si），并快速有效地将Si与其他阳离子物质分离。在整个过程中，Si的总回收率优于98%，并且没有产生Si同位素分馏。矩阵测试表明，这种方法是适合硅酸盐，和典型的硫酸盐和硝酸盐的河流沃茨丰度没有影响测量硅同位素组成。后一个方面是至关重要的分析河流沃茨，因为该技术不分离溶解的硅（硅酸）从周围的阴离子物种。总的来说，新方法提供了一种更快，更安全，更可靠的方法来通过MC-ICPMS测量Si同位素。(c)2006 Elsevier B.V保留所有权利。
Techniques for the purification of Si for the determination of its natural stable isotopic composition have in the past been based on the requirements for gas-source mass-spectrometry, rather than MC-ICPMS. For high precision analyses by MC-ICPMS it is essential to have very pure solutions and in this paper a new technique is presented for the separation and purification of Si from natural samples to improve the determination of isotope ratios. A method has been optimised based on alkaline fusion followed by ion-exchange chromatography. The application to natural samples, such as river water samples and silicate mineral/rock samples is demonstrated. Alkali fusion avoids the use of hydrofluoric acid (HF), which introduces difficulties for the deterrnination of Si isotope ratios using MC-ICPMS. By eliminating HF a 30-40% increase in sensitivity is achieved as well as a marked enhancement of mass bias stability leading to a factor of 2 improvement in reproducibility. The cation-exchange method enables processing of very small samples (3.6 mu g Si) and a rapid and effective separation of Si from other cationic species. The overall recovery of Si during the entire procedure is better than 98% and no Si isotope fractionation is generated. Matrix tests demonstrate that this method is suitable for silicates, and that typical sulphate and nitrate abundances of river waters have no effect on measured Si isotope composition. The latter aspect is vital for analysis of river waters since the technique does not separate dissolved Si (silicic acid) from ambient anionic species. Overall, the new method presents a faster, safer and more reliable way to measure Si isotopes via MC-ICPMS. (c) 2006 Elsevier B.V All rights reserved.