z-logo
Premium
Effects of different constants and standards on the reproducibility of carbonate clumped isotope (Δ 47 ) measurements: Insights from a long‐term dataset
Author(s) -
Chang Biao,
Defliese William F.,
Li Chao,
Huang Junhua,
Tripati Aradhna,
Algeo Thomas J.
Publication year - 2020
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.8678
Subject(s) - reproducibility , carbonate , chemistry , analytical chemistry (journal) , fractionation , isotope , isotopes of carbon , stable isotope ratio , isotope ratio mass spectrometry , isotope dilution , δ18o , oxygen isotope ratio cycle , dolomite , mineralogy , environmental chemistry , mass spectrometry , chromatography , total organic carbon , organic chemistry , physics , quantum mechanics
Rationale Carbonate clumped isotope (Δ 47 ) thermometry examines the temperature‐dependent excess abundance of the 13 C– 18 O bond in the carbonate lattice. Inconsistent temperature calibrations and standard values have been reported among laboratories, which has led to the use of equilibrated gases and carbonate standards for standardization. Furthermore, different acid fractionation factors and isotopic parameter sets have been proposed for improving inter‐laboratory data comparability. However, few long‐term datasets have been generated to explore the effects of these factors on the long‐term reproducibility of Δ 47 data within a laboratory. Methods Four standards (ISTB‐1, NBS‐19, GBWO4416, and GB04417) were analyzed as unknowns by isotope ratio mass spectrometry from 2015 to 2019. The values of Δ 47 were calibrated using the ETH standards. We investigated the Assonov, Brand, and Gonfiantini isotope parameter sets for carbon and oxygen isotopes, as well as two correction schemes of equilibrated gas and carbonate standardization, using the same sample measurements to determine which procedures enhanced reproducibility. ISTB‐1 (calcite) and ZK312‐346W (dolomite) were measured to determine the 90°C acid fractionation factor. Results The corrected 90°C acid fractionation factors are 0.076 ± 0.008‰ for ISTB‐1 and 0.077 ± 0.009‰ for ZK312‐346W. The choice of isotope parameter set had no significant influence on final Δ 47 values in this study. However, using the Assonov parameters to calculate Δ 47 values improved the reproducibility of the results. The use of carbonate standards improved reproducibility through time compared with the use of equilibrated gases for standardization. Conclusions At 90°C, the acid fractionation factors of calcite and dolomite are statistically indistinguishable. We find an insignificant effect from changing the isotope parameter set, suggesting that the choice of isotope parameter set among laboratories is not a major factor affecting inter‐laboratory reproducibility. We find that using carbonate standards improved the reproducibility of results, suggesting that the use of carbonate standards may help to achieve inter‐laboratory comparability of results in future studies.

This content is not available in your region!

Continue researching here.

Having issues? You can contact us here