Precision and long-term stability of clumped isotope analysis of CO2by a small sector isotope ratio mass spectrometer
Precision and long-term stability of clumped isotope analysis of CO2by a small sector isotope ratio mass spectrometer
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小扇区同位素比质谱仪对 CO2 聚集同位素分析的精度和长期稳定性
DOI：
10.1002/rcm.6431
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发表时间：
2013
影响因子：
2
通讯作者：
Naohiro Yoshida
中科院分区：
文献类型：
--
作者：
Y. Kawamoto;M. Eto;T. Okabe;Y. Obayashi;T. Kaneko;J. Takahashi;H. Mita;K. Kanda;K. Kobayashi;Naohiro Yoshida
由碳酸盐矿物的δ13C和δ18O值决定的13c - 18o键合co2的测量丰度与随机丰度之比对其生长温度敏感。近年来，利用这一比值的团块同位素测温法已被用作定量解释古温度的新工具。方法用小扇形同位素比值质谱仪测定co2中的团块同位素。用低温和气相色谱分离纯化了几种碳酸钙在25°C下经磷酸消化的co2样品，然后用双入口Delta XP质谱仪测定了它们的同位素组成（δ13C, δ18O， Δ47， Δ48and Δ49values）。结果单气体Δ47measurements在最佳分析条件和常规分析条件下的内部精密度分别为0.005和0.02‰（1 SE），与MAT 253质谱仪的内部精密度相当。自2007年以来，室内工作标准和加热co2气体的Δ47values的长期变化接近常规的单一气体不确定性，同时显示出季节性的周期性，并呈下降趋势。与MAT 253不同，Delta XP没有显示Δ47and δ47值之间的任何显著关系。结论Delta XP提供的结果与MAT 253的结果大致相同，用于团块同位素分析。Delta XP的时间稳定性似乎较低，尽管Delta XP的一个优点是δ47不依赖于Δ47was。版权所有©2012 John Wiley & Sons， Ltd。
RATIONALEThe ratio of the measured abundance of13C–18O bonding CO2to its stochastic abundance, prescribed by the δ13C and δ18O values from a carbonate mineral, is sensitive to its growth temperature. Recently, clumped‐isotope thermometry, which uses this ratio, has been adopted as a new tool to elucidate paleotemperatures quantitatively.METHODSClumped isotopes in CO2were measured with a small‐sector isotope ratio mass spectrometer. CO2samples digested from several kinds of calcium carbonates by phosphoric acid at 25 °C were purified using both cryogenic and gas‐chromatographic separations, and their isotopic composition (δ13C, δ18O, Δ47, Δ48and Δ49values) were then determined using a dual‐inlet Delta XP mass spectrometer.RESULTSThe internal precisions of the single gas Δ47measurements were 0.005 and 0.02 ‰ (1 SE) for the optimum and the routine analytical conditions, respectively, which are comparable with those obtained using a MAT 253 mass spectrometer. The long‐term variations in the Δ47values for the in‐house working standard and the heated CO2gases since 2007 were close to the routine, single gas uncertainty while showing seasonal‐like periodicities with a decreasing trend. Unlike the MAT 253, the Delta XP did not show any significant relationship between the Δ47and δ47values.CONCLUSIONSThe Delta XP gave results that were approximately as precise as those of the MAT 253 for clumped‐isotope analysis. The temporal stability of the Delta XP seemed to be lower, although an advantage of the Delta XP was that no dependency of δ47on Δ47was found. Copyright © 2012 John Wiley & Sons, Ltd.