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Yan Q, Zhao Y, Ma R, Wang B, Zhu Z, Li T, He D, Hocart CH, Zhou Y. Capping the hydroxyl groups (-OH) of α-cellulose to reduce Hy-groscopicity for accurate 18O/ 16O measurement by EA/Py/IRMS. Talanta 2023; 262:124698. [PMID: 37244243 DOI: 10.1016/j.talanta.2023.124698] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 05/18/2023] [Accepted: 05/21/2023] [Indexed: 05/29/2023]
Abstract
Obtaining an accurate measurement of 18O/16O at natural abundance level for land plants-derived α-cellulose with the currently popular EA/Py/IRMS (elemental analysis/pyrolysis/isotope ratio mass spectrometry) method is a challenge due to the hygroscopic nature of the exposed hydroxyl groups, as the 18O/16O of adsorbed moisture is usually different from that of the α-cellulose and the relative amount of adsorbed moisture is sample- and relative humidity-dependent. To minimize the hygroscopicity-related measurement error, we capped the hydroxyl groups of α-cellulose by benzylation to various degrees and found that the 18O/16O ratio of α-cellulose increased with the degree of benzyl substitution (DS), consistent with the theoretical prediction that a reduced presence of exposed hydroxyl groups should lead to a more accurate (and therefore more reliable) α-cellulose 18O/16O measurement. We propose the establishment of a moisture adsorption-degree of substitution or percentage of oxygen-18O/16O ratio equation, based on the measurement of C%, O% and δ18O of variably capped α-cellulose, so that a robust correction can be made in a plant species- and laboratory conditions-specific manner. Failure to do so will lead to an average underestimate of α-cellulose δ18O by 3.5 mUr under "average" laboratory conditions.
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Affiliation(s)
- Qiulin Yan
- Isotopomics in Chemical Biology (ICB), School of Chemistry and Chemical Engineering, Shaanxi University of Science and Technology, Xi'an, 710021, China
| | - Yu Zhao
- Isotopomics in Chemical Biology (ICB), School of Chemistry and Chemical Engineering, Shaanxi University of Science and Technology, Xi'an, 710021, China
| | - Ran Ma
- Isotopomics in Chemical Biology (ICB), School of Chemistry and Chemical Engineering, Shaanxi University of Science and Technology, Xi'an, 710021, China
| | - Bo Wang
- Isotopomics in Chemical Biology (ICB), School of Chemistry and Chemical Engineering, Shaanxi University of Science and Technology, Xi'an, 710021, China
| | - Zhenyu Zhu
- Isotopomics in Chemical Biology (ICB), School of Chemistry and Chemical Engineering, Shaanxi University of Science and Technology, Xi'an, 710021, China
| | - Ting Li
- College of Science and Engineering, ARC Centre of Excellence for Australian Biodiversity and Heritage, Centre for Tropical Environmental and Sustainability Science, James Cook University, Cairns, 4878, Australia
| | - Ding He
- Department of Ocean Science and Center for Ocean Research in Hong Kong and Macau, The Hong Kong University of Science and Technology, Hong Kong SAR, China; State Key Laboratory of Marine Pollution, Hong Kong, China
| | - Charles H Hocart
- Isotopomics in Chemical Biology (ICB), School of Chemistry and Chemical Engineering, Shaanxi University of Science and Technology, Xi'an, 710021, China; Research School of Biology, Australian National University, Acton, 2601, ACT, Australia
| | - Youping Zhou
- Isotopomics in Chemical Biology (ICB), School of Chemistry and Chemical Engineering, Shaanxi University of Science and Technology, Xi'an, 710021, China; Isotopomics in Chemical & Biological Oceanography (ICBO), Department of Ocean Science and Engineering, Southern University of Science and Technology, Shenzhen, 518055, China.
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