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Precision and long‐term stability of clumped‐isotope analysis of CO 2 using a small‐sector isotope ratio mass spectrometer
Author(s) -
Yoshida Naohiro,
Vasilev Mikhail,
Ghosh Prosenjit,
Abe Osamu,
Yamada Keita,
Morimoto Maki
Publication year - 2012
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.6431
Subject(s) - chemistry , isotope , stable isotope ratio , analytical chemistry (journal) , natural abundance , mass spectrometry , isotope ratio mass spectrometry , isotope analysis , isotopic ratio , isotopes of carbon , delta , abundance (ecology) , mineralogy , environmental chemistry , chromatography , geology , ecology , physics , oceanography , quantum mechanics , aerospace engineering , total organic carbon , engineering , biology
RATIONALE The ratio of the measured abundance of 13 C– 18 O bonding CO 2 to its stochastic abundance, prescribed by the δ 13 C and δ 18 O 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 CO 2 were measured with a small‐sector isotope ratio mass spectrometer. CO 2 samples 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 (δ 13 C, δ 18 O, Δ 47 , Δ 48 and Δ 49 values) were then determined using a dual‐inlet Delta XP mass spectrometer. RESULTS The internal precisions of the single gas Δ 47 measurements 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 Δ 47 values for the in‐house working standard and the heated CO 2 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 Δ 47 and δ 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 δ 47 on Δ 47 was found. Copyright © 2012 John Wiley & Sons, Ltd.