High-precision and high-accuracy magnesium isotope analysis on multiple-collector inductively coupled plasma mass spectrometry using a critical mixture double spike technique
Yongsheng He , Ai-Ying Sun , Yin-Chu Zhang , Ru-Yi Yang , Shan Ke , Yang Wang (汪洋) , Fang-Zhen Teng
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引用次数: 2
Abstract
A new procedure has been developed for high precision and high accuracy Mg isotope analysis on multiple-collector inductively coupled plasma mass spectrometry using a critical mixture double spike technique. Errors arising from improper preparation of the critical double spike solutions are able to be corrected against the regression on a set of over- and under-spiked standards. Accuracy is ensured by correcting mass bias offset based on Monte Carlo calculations. Doping experiments indicate that the double spike method is robust to non-spectrum matrix effects. A long-term precision and accuracy of ±0.03‰ (2SD) was demonstrated for δ26Mg by replicate analyses of well-characterized in-house pure Mg solutions and synthetic samples passed through the column chemistry, provided that each sample was measured four times. The robustness of the method was further assessed by replicate analyses of fifteen geological reference materials ranging from peridotite, basalt, granodiorite, carbonatite to seawater. Rock standards yielded consistently higher δ26Mg by 0.076 ± 0.052‰ (2SD, N = 12) compared to data previously reported by standard-sample-bracketing from the same lab. This discrepancy might result from the difficulty in matching the matrices of natural samples exactly the same to the bracketing standards, even after purification, suggesting a careful evaluation on residual matrix effect for the standard-sampling-bracketing method. Our new data for geological reference materials serve as a reference for quality assessment and inter-laboratory comparison in future studies.
采用临界混合双尖峰技术,建立了一种高精度、高精度的多集热器电感耦合等离子体质谱分析Mg同位素的新方法。由临界双尖峰溶液制备不当引起的错误可以通过对一组尖峰过高和过低标准的回归来纠正。通过校正基于蒙特卡罗计算的质量偏差偏移来保证精度。掺杂实验表明,双尖峰法对非谱矩阵效应具有较强的鲁棒性。通过重复分析表征良好的内部纯Mg溶液和通过柱化学的合成样品,证明了δ26Mg的长期精密度和准确度为±0.03‰(2SD),只要每个样品测量四次。通过对橄榄岩、玄武岩、花岗闪长岩、碳酸岩、海水等15种地质参考物质的重复分析,进一步评估了该方法的稳健性。岩石标准样品的δ26Mg比先前同一实验室的标准样品包套法报告的数据高0.076±0.052‰(2SD, N = 12)。这种差异可能是由于即使在纯化后,自然样品的矩阵也难以与包封标准完全匹配,这表明需要仔细评估标准取样-包封方法的剩余矩阵效应。我们的新数据为今后的研究提供了质量评价和实验室间比较的参考。