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Precision and long-term stability of clumped-isotope analysis of CO2 using a small-sector isotope ratio mass spectrometer

Yoshida, Naohiro and Vasilev, Mikhail and Ghosh, Prosenjit and Abe, Osamu and Yamada, Keita and Morimoto, Maki (2013) Precision and long-term stability of clumped-isotope analysis of CO2 using a small-sector isotope ratio mass spectrometer. In: RAPID COMMUNICATIONS IN MASS SPECTROMETRY, 27 (1). pp. 207-215.

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Official URL: http://dx.doi.org/10.1002/rcm.6431


RATIONALE The ratio of the measured abundance of 13C18O bonding CO2 to its stochastic abundance, prescribed by the delta 13C and delta 18O 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. METHODS Clumped isotopes in CO2 were measured with a small-sector isotope ratio mass spectrometer. CO2 samples digested from several kinds of calcium carbonates by phosphoric acid at 25 degrees C were purified using both cryogenic and gas-chromatographic separations, and their isotopic composition (delta 13C, delta 18O, Delta 47, Delta 48 and Delta 49 values) were then determined using a dual-inlet Delta XP mass spectrometer. RESULTS The internal precisions of the single gas Delta 47 measurements were 0.005 and 0.02 parts per thousand (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 Delta 47 values for the in-house working standard and the heated CO2 gases 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 Delta 47 and delta 47 values. CONCLUSIONS The 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 delta 47 on Delta 47 was found. Copyright (c) 2012 John Wiley & Sons, Ltd.

Item Type: Journal Article
Additional Information: Copyright for this article belongs to WILEY-BLACKWELL.USA
Department/Centre: Division of Mechanical Sciences > Centre for Earth Sciences
Date Deposited: 28 Jan 2013 07:36
Last Modified: 28 Jan 2013 07:36
URI: http://eprints.iisc.ac.in/id/eprint/45652

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