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An interlaboratory study of TEX86 and BIT analysis using high-performance liquid chromatography-mass spectrometry

Lookup NU author(s): Dr Emma PearsonORCiD, Dr Antoni Rosell-Mele, Dr Syed Shah, Dr Helen Talbot

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Abstract

Recently, two new proxies based on the distribution of glycerol dialkyl glycerol tetraethers (GDGTs) were proposed, i.e., the TEX86 proxy for sea surface temperature reconstructions and the BIT index for reconstructing soil organic matter input to the ocean. In this study, fifteen laboratories participated in a round robin study of two sediment extracts with a range of TEX86 and BIT values to test the analytical reproducibility and repeatability in analyzing these proxies. For TEX86 the repeatability, indicating intralaboratory variation, was 0.028 and 0.017 for the two sediment extracts or ±1-2°C when translated to temperature. The reproducibility, indicating among-laboratory variation, of TEX86 measurements was substantially higher, i.e., 0.050 and 0.067 or 7plusmn;3-4°C when translated to temperature. The latter values are higher than those obtained in round robin studies of Mg/Ca and U κ′37 paleothermometers, suggesting the need to primarily improve compatibility between labs. The repeatability of BIT measurements for the sediment with substantial amounts of soil organic matter input was relatively small, 0.029, but reproducibility was large, 0.410. This large variance could not be attributed to specific equipment used or a particular data treatment. We suggest that this may be caused by the large difference in the molecular weight in the GDGTs used in the BIT index, i.e., crenarchaeol versus the branched GDGTs. Potentially, this difference gives rise to variable responses in the different mass spectrometers used. Calibration using authentic standards is needed to establish compatibility between labs performing BIT measurements. © 2009 by the American Geophysical Union.

Publication metadata

Author(s): Schouten S, Hopmans E, Van Der Meer J, Mets A, Bard E, Bianchi T, Diefendorf A, Escala M, Freeman K, Furukawa Y, Huguet C, Ingalls A, Ménot-Combes G, Nederbragt A, Oba M, Pearson A, Pearson E, Rosell-Melé A, Schaeffer P, Shah S, Shanahan T, Smith R, Smittenberg R, Talbot H, Uchida M, Van Mooy B, Yamamoto M, Zhang Z, Damsté J

Publication type: Article

Publication status: Published

Journal: Geochemistry, Geophysics, Geosystems

Year: 2009

Volume: 10

Issue: 3

ISSN (print): 1525-2027

ISSN (electronic):

Publisher: American Geophysical Union

URL: http://dx.doi.org/10.1029/2008GC002221

DOI: 10.1029/2008GC002221

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