Sulfur isotope measurement of sulfate and sulfide by high-resolution MC-ICP-MS
Sulfur isotope measurement of sulfate and sulfide by high-resolution MC-ICP-MS
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DOI：
10.1016/j.chemgeo.2008.04.017
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发表时间：
2008-08-15
期刊：
影响因子：
3.9
通讯作者：
Bach, Wolfgang
中科院分区：
文献类型：
--
作者：
Craddock, Paul R.;Rouxel, Olivier J.;Bach, Wolfgang
采用溶液-激光烧蚀多接收电感耦合等离子体质谱（MC-ICP-MS）技术，建立了一种准确、精密测定含硫矿物中δ（34）S/（32）S同位素比值的方法。我们已经检查并确定了严格的校正分析困难，如仪器质量偏差，未解决的同量异位素干扰，空白，激光烧蚀和基质诱导的同位素分馏。使用高分辨率扇形保持质谱法可以消除O（2）（+）的主要同量异位素干扰。标准品交叉进样用于校正未知样品的仪器质量偏差。由记忆效应和残留氧拖尾引起的硫质量背景通常很小（< 0.2份/千，在分析误差范围内），并且通过峰上减零和将样品与在相同信号强度下测定的标准品进行括号化来数学消除（20%以内）。基质效应对于与许多天然含硫矿物相关的基质组合物是显著的（高达0.7份/千）。对于溶液分析，硫同位素组成最好使用纯化的（基质清洁）硫标准品和样品溶液使用我们提出的化学纯化方案来确定。对于原位分析，其中在分析之前不能去除复杂基质，适当的基质匹配标准品和样品去除基质伪影并产生与使用基质清洁分析物的常规技术一致的硫同位素比率。我们的方法使固体样品进行校准，对水的标准;一个考虑是很重要的认证时，同位素均匀和适当的基质匹配的固体标准不存在。此外，批量和原位分析可以在单个分析会话中互换地进行，因为仪器设置对于两者是相同的。我们通过对一系列参比物质的多种同位素分析验证了我们分析方法的稳健性，并将其与使用独立技术测定的同位素比进行了比较。S同位素组成的长期重现性通常为0.20%。0.45%。（2 σ）分别用于溶液和激光分析。该方法可对广泛的含硫物质进行准确和相对精确的硫同位素测量，特别适用于基质复杂、高分辨率原位分析至关重要的地质样品。(C)2008 Elsevier B. V.保留所有权利。
We have developed a technique for the accurate and precise determination of (34)S/(32)S isotope ratios (delta(34)S) in sulfur-bearing minerals using solution and laser ablation multiple-col lector inductively coupled plasma mass spectrometry (MC-ICP-MS). We have examined and determined rigorous corrections for analytical difficulties such as instrumental mass bias, unresolved isobaric interferences, blanks, and laser ablation- and matrix-induced isotopic fractionation. Use of high resolution sector-held mass spectrometry removes major isobaric interferences from O(2)(+). Standard-sample bracketing is used to correct for the instrumental mass bias of unknown samples. Background on sulfur masses arising from memory effects and residual oxygen-tailing are typically minor (< 0.2 parts per thousand, within analytical error), and are mathematically removed by on-peak zero subtraction and by bracketing of samples with standards determined at the same signal intensity (within 20%). Matrix effects are significant (up to 0.7 parts per thousand) for matrix compositions relevant to many natural sulfur-bearing minerals. For solution analysis, sulfur isotope compositions are best determined using purified (matrix-clean) sulfur standards and sample solutions using the chemical purification protocol we present, For in situ analysis, where the complex matrix cannot be removed prior to analysis, appropriately matrix-matching standards and samples removes matrix artifacts and yields Sulfur isotope ratios consistent with conventional techniques using matrix-clean analytes. Our method enables solid samples to be calibrated against aqueous standards; a consideration that is important when certified, isotopically-homogeneous and appropriately matrix-matched solid standards do not exist. Further, bulk and in situ analyses can be performed interchangeably in a single analytical session because the instrumental setup is identical for both. We validated the robustness of our analytical method through multiple isotope analyses of a range of reference materials and have compared these with isotope ratios determined using independent techniques. Long-term reproducibility of S isotope compositions is typically 0.20%. and 0.45%. (2 sigma) for solution and laser analysis, respectively. Our method affords the opportunity to make accurate and relatively precise S isotope measurement for a wide range of sulfur-bearing materials, and is particularly appropriate for geologic samples with complex matrix and for which high-resolution in situ analysis is critical. (C) 2008 Elsevier B.V. All rights reserved.