Capping the hydroxyl groups (-OH) of α-cellulose to reduce Hy-groscopicity for accurate 18O/16O measurement by EA/Py/IRMS

Qiulin Yan, Yu Zhao, Ran Ma, Bo Wang, Zhenyu Zhu, Ting Li, Ding He, Charles H. Hocart, Youping Zhou*

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    1 Citation (Scopus)

    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.

    Original languageEnglish
    Article number124698
    JournalTalanta
    Volume262
    DOIs
    Publication statusPublished - 1 Sept 2023

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