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Simultaneous, High-Precision Measurements of δ²H and δ¹³C in Nanomole Quantities of Acetate Using Electrospray Ionization-Quadrupole-Orbitrap Mass Spectrometry

Mueller, Elliott P. and Sessions, Alex L. and Sauer, Peter E. and Weiss, Gabriella M. and Eiler, John M. (2022) Simultaneous, High-Precision Measurements of δ²H and δ¹³C in Nanomole Quantities of Acetate Using Electrospray Ionization-Quadrupole-Orbitrap Mass Spectrometry. Analytical Chemistry, 94 (2). pp. 1092-1100. ISSN 0003-2700. doi:10.1021/acs.analchem.1c04141. https://resolver.caltech.edu/CaltechAUTHORS:20220114-12564000

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Abstract

Stable hydrogen isotope compositions (²H/¹H ratios) have been an invaluable tool for studying biogeochemical processes in nature, but the diversity of molecular targets amenable to such analysis is limited. Here, we demonstrate a new technique for measuring δ²H of biomolecules via Orbitrap mass spectrometry (MS) using acetate as a model analyte. Acetate was chosen as a target molecule because its production and consumption are central to microbial carbon cycling, yet the mechanisms behind acetate turnover remain poorly understood. δ²H of acetate could provide a useful constraint on these processes; however, it remains uncharacterized in nature due to analytical challenges. Electrospray ionization (ESI)-Orbitrap MS circumvents these challenges and delivers methyl-specific H-isotope compositions of acetate with nanomole sensitivity, enough to enable analyses of environmental samples. This approach quantifies the methyl-specific δ²H and molecular-average δ¹³C of acetate simultaneously while achieving <3 and <0.5‰ uncertainty, respectively. Using optimized ionization and Orbitrap parameters, this level of precision is obtained within 15 min using only 15 nmol of acetate. As a demonstration of our analytical approach, we cultured three acetogenic bacteria and found a large ²H-fractionation between acetate and water (>310‰ depletion) associated with the Wood–Ljungdahl pathway, while fermentation expressed a muted (∼80‰) fractionation. With its high precision and sensitivity, Orbitrap MS is a promising tool for investigating these signals in nature after offline purification. Furthermore, the ESI-Orbitrap method presented here could be applied to other molecules amenable to ESI, including central metabolites and sugars, greatly expanding the molecular targets used in hydrogen isotope biogeochemistry.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1021/acs.analchem.1c04141DOIArticle
ORCID:
AuthorORCID
Mueller, Elliott P.0000-0002-6837-0409
Sessions, Alex L.0000-0001-6120-2763
Weiss, Gabriella M.0000-0002-9571-2558
Eiler, John M.0000-0001-5768-7593
Alternate Title:Simultaneous, High-Precision Measurements of δ2H and δ13C in Nanomole Quantities of Acetate Using Electrospray Ionization-Quadrupole-Orbitrap Mass Spectrometry
Additional Information:© 2021 American Chemical Society. Received: September 23, 2021; Accepted: December 20, 2021; Published: December 30, 2021. The authors gratefully acknowledge Jared Leadbetter and Victoria Orphan (Caltech) for use of their laboratory spaces, Nathan Dalleska (Environmental Analysis Center, Caltech) for expertise in the ion chromatography system, Volker Müller (Goethe University, Frankfurt, Germany) for providing both strains of autotrophic acetogens, Tim Csernica, Sarah Zeichner, and Elise Wilkes for providing data analysis scripts, and Fenfang Wu (Caltech) for assistance with EA-IRMS measurements. This work was made possible by an NSF Graduate Research Fellowship DGE-1745301 (to E.P.M.) and the NASA Astrobiology Institute grant # 80NSSC18M0094 (to J.M.E. and A.L.S.). Author Contributions. E.P.M initiated the project and performed ESI-Orbitrap and IC experiments. E.P.M. and G.M.W. grew bacterial cultures. P.E.S. carried out TC-EA-IRMS experiments. E.P.M., A.L.S., and J.M.E interpreted experimental data. All authors contributed to writing the manuscript. The authors declare no competing financial interest.
Funders:
Funding AgencyGrant Number
NSF Graduate Research FellowshipDGE-1745301
NASA80NSSC18M0094
Subject Keywords:Hydrogen isotopes, Organic compounds, Mass spectrometry, Isotopes, Ions
Issue or Number:2
DOI:10.1021/acs.analchem.1c04141
Record Number:CaltechAUTHORS:20220114-12564000
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20220114-12564000
Official Citation:Simultaneous, High-Precision Measurements of δ2H and δ13C in Nanomole Quantities of Acetate Using Electrospray Ionization-Quadrupole-Orbitrap Mass Spectrometry. Elliott P. Mueller, Alex L. Sessions, Peter E. Sauer, Gabriella M. Weiss, and John M. Eiler. Analytical Chemistry 2022 94 (2), 1092-1100; DOI: 10.1021/acs.analchem.1c04141
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:112919
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:18 Jan 2022 15:26
Last Modified:18 Jan 2022 18:34

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