A comparison of isotope ratio mass spectrometry and cavity ring‐down spectroscopy techniques for isotope analysis of fluid inclusion water
A comparison of isotope ratio mass spectrometry and cavity ring‐down spectroscopy techniques for isotope analysis of fluid inclusion water
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DOI：
10.1002/rcm.8837
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发表时间：
2020-07
影响因子：
2
通讯作者：
S. Graaf;H. Vonhof;Therese Weissbach;J. Wassenburg;E. Levy;T. Kluge;G. Haug
中科院分区：
文献类型：
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作者：
S. Graaf;H. Vonhof;Therese Weissbach;J. Wassenburg;E. Levy;T. Kluge;G. Haug
矿物包裹体水的氧（δ18 O）、氢（δ2 H）同位素在线分析在古流体研究中应用广泛。然而，在流体包裹体同位素研究的最新技术中，缺乏报告的技术间比较来解释可能的分析偏移。沿着分析精度的提高和样本量的限制，实验室间的比较可以导致流体包裹体同位素记录的更可靠的应用。方法采用两套新建立的流体包裹体同位素分析系统对洞穴沉积物、碳酸盐岩和脉体进行分析，以提供平台间的对比。一种设置使用在线连接到连续流热解炉和同位素比质谱（IRMS）仪器的破碎机单元。在另一种装置中，破碎机装置与光腔衰荡光谱（CRDS）系统相连接，在连续标准水背景下分析水样，以实现注入水的精确度：δ18 O值优于0.1‰，δ2 H值优于0.4‰，注入量低至0.2 μL。结果在IRMS装置上进行流体包裹体同位素分析，δ18 O和δ2 H的1σ平均重复性分别为0.4‰和2.0‰。CRDS装置具有更好的1σ重现性（δ18 O值为0.3‰，δ2 H值为1.1‰）和更快的样品通量（<30 min/样品）。流体包裹体同位素分析在这些不确定度下可重复，水量低至0.1 μL。流体包裹体同位素数据显示，没有系统的设置之间的偏移。结论：两种装置之间流体包裹体同位素结果的密切匹配证明了所提出的用于流体包裹体同位素分析的连续流技术的高准确性。理想情况下，如在这项研究中提出的实验将导致进一步的实验室间比较的努力和选择合适的参考材料的流体包裹体同位素研究。
RATIONALE Online oxygen (δ18 O) and hydrogen (δ2 H) isotope analysis of fluid inclusion water entrapped in minerals is widely applied in paleo-fluid studies. In the state of the art of fluid inclusion isotope research, however, there is a scarcity of reported inter-technique comparisons to account for possible analytical offsets. Along with improving analytical precisions and sample size limitations, interlaboratory comparisons can lead to a more robust application of fluid inclusion isotope records. METHODS Mineral samples-including speleothem, travertine, and vein material-were analyzed on two newly setup systems for fluid inclusion isotope analysis to provide an inter-platform comparison. One setup uses a crusher unit connected online to a continuous-flow pyrolysis furnace and an isotope ratio mass spectrometry (IRMS) instrument. In the other setup, a crusher unit is lined up with a cavity ring-down spectroscopy (CRDS) system, and water samples are analyzed on a continuous standard water background to achieve precisions on water injections better than 0.1‰ for δ18 O values and 0.4‰ for δ2 H values for amounts down to 0.2 μL. RESULTS Fluid inclusion isotope analyses on the IRMS setup have an average 1σ reproducibility of 0.4‰ and 2.0‰ for δ18 O and δ2 H values, respectively. The CRDS setup has a better 1σ reproducibility (0.3‰ for δ18 O values and 1.1‰ for δ2 H values) and also a more rapid sample throughput (<30 min per sample). Fluid inclusion isotope analyses are reproducible at these uncertainties for water amounts down to 0.1 μL on both setups. Fluid inclusion isotope data show no systematic offsets between the setups. CONCLUSIONS The close match in fluid inclusion isotope results between the two setups demonstrates the high accuracy of the presented continuous-flow techniques for fluid inclusion isotope analysis. Ideally, experiments such as the one presented in this study will lead to further interlaboratory comparison efforts and the selection of suitable reference materials for fluid inclusion isotopes studies.