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Three wood isotopic reference materials for δ²H and δ¹³C measurements of plant methoxy groups

Greule, Markus and Moossen, Heiko and Lloyd, Max K. and Geilmann, Heike and Brand, Willi A. and Eiler, John M. and Qi, Haiping and Keppler, Frank (2020) Three wood isotopic reference materials for δ²H and δ¹³C measurements of plant methoxy groups. Chemical Geology, 533 . Art. No. 119428. ISSN 0009-2541. https://resolver.caltech.edu/CaltechAUTHORS:20191125-144250913

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Abstract

Methoxy groups (OCH₃) of plants show specific stable carbon and hydrogen isotope patterns that are used for applications in biogeochemical, atmospheric, paleoclimatic and food research. The method of choice for determining stable hydrogen and carbon isotope values of methoxy groups (δ²H_(OCH₃) and δ¹³C_(OCH₃) values) is the conversion to gaseous iodomethane (CH₃I) and subsequent measurement by stable isotope ratio mass spectrometry. However, comparative measurements particularly for stable hydrogen isotopes of plant methoxy groups are limited due to the lack of suitable reference materials. We have prepared three batches of powdered wood samples (birch HUBG3, beech HUBG4, and tineo HUBG5) collected from different geographical locations to serve as long-term reference materials for normalization of δ²H_(OCH₃) but also δ¹³C_(OCH₃) values. Methoxy contents of the three wood samples range between 4.7 and 5.4%. Methoxy groups from subsamples of the three homogenized wood samples were quantitatively converted to CH₃I and δ²H_(OCH₃) and δ¹³C(OCH₃) values of this CH₃I were calibrated against international reference substances by high-temperature conversion- and elemental analyzer isotope ratio mass spectrometry. The δ²H_(OCH) and δ¹³C_(OCH₃) values of HUBG3 and HUBG4 at 1σ uncertainty calibrated to the VSMOW and VPDB isotopic δ-scale, respectively are −272.9 ± 1.5 mUr and −29.40 ± 0.13 mUr; and −239.1 ± 1.4 mUr and −30.17 ± 0.13 mUr, respectively. In addition, the calibrated δ²HOCH value of HUBG5 is −191.7 ± 0.8 mUr. Whilst the δ²H_(OCH₃) values of the three wood samples span a relatively wide range (~−280 to −190 mUr) suitable for normalization of δ²H_(OCH₃) values of most plant samples that have been reported so far, δ¹³C_(OCH₃) values are restricted to a composition (~−30 mUr) typical of wood methoxy groups. We suggest that the three investigated wood materials HUBG3–5 are ideally suited for long-term usage, inter-laboratory comparison, and together with the two recently reported methyl sulfate salts (HUBG1 and HUBG2) complete a new set of solid methoxy reference materials that cover almost the full range of plant methoxy groups reported so far. Therefore, we recommend replacing liquid CH₃I and instead use the solid reference materials set HUBG1–5 for normalizing δ²H_(OCH₃) and δ¹³C_(OCH₃) values to the respective δ-scales.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1016/j.chemgeo.2019.119428DOIArticle
ORCID:
AuthorORCID
Greule, Markus0000-0002-9958-8371
Lloyd, Max K.0000-0001-9367-2698
Additional Information:© 2019 Published by Elsevier B.V. Received 6 August 2019, Revised 21 November 2019, Accepted 22 November 2019, Available online 25 November 2019. We thank Axel Groh from the company Schorn & Groh veneers for providing slices of birch and tineo wood, the carpentry of the youth institution “Stift Sunnisheim”, Hendric Glatting for the homogenization of the wood samples and Timo Schreiter for measurements of methoxy quantification. This study was supported by the German Science Foundation DFG (KE 884/6-3, KE 884/8-2). The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Funders:
Funding AgencyGrant Number
Deutsche Forschungsgemeinschaft (DFG)KE 884/6-3
Deutsche Forschungsgemeinschaft (DFG)KE 884/8-2
Subject Keywords:Plant methoxy groups; Solid reference materials; Stable hydrogen isotopes; Stable carbon isotopes; Stable isotope mass spectrometry
Record Number:CaltechAUTHORS:20191125-144250913
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20191125-144250913
Official Citation:Markus Greule, Heiko Moossen, Max K. Lloyd, Heike Geilmann, Willi A. Brand, John M. Eiler, Haiping Qi, Frank Keppler, Three wood isotopic reference materials for δ2H and δ13C measurements of plant methoxy groups, Chemical Geology, Volume 533, 2020, 119428, ISSN 0009-2541, https://doi.org/10.1016/j.chemgeo.2019.119428. (http://www.sciencedirect.com/science/article/pii/S0009254119305571)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:100045
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:25 Nov 2019 23:06
Last Modified:10 Dec 2019 20:50

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