Determination of mass-dependent molybdenum isotopic variations by MC-ICP-MS: An evaluation of matrix effects
Determination of mass-dependent molybdenum isotopic variations by MC-ICP-MS: An evaluation of matrix effects
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DOI：
10.1016/j.chemgeo.2005.09.002
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发表时间：
2006-01
期刊：
影响因子：
3.9
通讯作者：
A. Pietruszka;R. Walker;P. Candela
中科院分区：
文献类型：
--
作者：
A. Pietruszka;R. Walker;P. Candela
目前有几种分析技术用于使用多接收器电感耦合等离子体质谱法（MC-ICP-MS）确定天然物质中质量相关的钼同位素变化，包括从样品中分离钼的不同方法和仪器质量相关同位素分馏（仪器质量偏差）的校正。在以前的研究中，已经使用了内部（使用两种富集钼同位素的"双掺"）和外部（"锆掺杂"与标准样品括号）技术来处理仪器质量偏差的影响。这些研究的结果表明，天然（含基质）样品的钼同位素分析的精确度是一个因素的1.4 - 7倍，更好地使用双加标。在这里，我们提出了一个详细的研究MC-ICP-MS的能力，以确定，准确和准确地，钼的同位素组成提取的辉沸石使用低空白，高产率的两列程序钼分离和一个简单的标准样品的括号法，以纠正仪器质量偏差。基于对钙钛矿的分析，该技术的精度与已发表的双峰数据相似（在1/2的因子内）。所有三种已知类型的潜在的MC-ICP-MS中的基体效应也进行了评价：自动基体效应，基体效应由于Zr掺杂和基体效应由于在样品中的元素以外的钼和锆。这些矩阵效应中的每一个被发现是微不足道的或可控的。五个热液成因的辉长岩的分析揭示了其钼同位素组成的范围，这是一个因素的104倍以上，比以前的范围内报告的此类样品。需要更详细的工作，以阐明这些质量依赖钼同位素的变化在辉长岩的起源。
Several analytical techniques are currently used to determine mass-dependent molybdenum isotopic variations in natural materials using multiple-collector inductively coupled plasma mass spectrometry (MC-ICP-MS), including different methods for the separation of Mo from the sample and the correction for instrumental mass-dependent isotopic fractionation (instrumental mass bias). Both internal (“double-spiking” using two enriched Mo isotopes) and external (“zirconium doping” with standard-sample bracketing) techniques have been used in previous studies to deal with the effects of instrumental mass bias. The results of these studies have indicated that the precision for Mo isotopic analyses of natural (matrix-bearing) samples is a factor of ∼4–7× better using a double spike. Here we present a detailed study of the ability of MC-ICP-MS to determine, both precisely and accurately, the isotopic composition of Mo extracted from molybdenite using a low blank, high yield two-column procedure for Mo separation and a simple standard-sample bracketing approach to correct for instrumental mass bias. Based on analyses of molybdenites, the precision of this technique is shown to be similar to published double-spike data (within a factor of ∼2). All three of the known types of potential matrix effects in the MC-ICP-MS are also evaluated: automatrix effects, matrix effects due to Zr doping and matrix effects due to elements in the sample other than Mo and Zr. Each of these matrix effects is found to be either insignificant or controllable. Analyses of five molybdenites of hydrothermal origin reveal a range in their Mo isotopic composition that is a factor of ∼4 greater than the previous range reported for such samples. More detailed work is required to elucidate the origin of these mass-dependent Mo isotopic variations in molybdenites.