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Boreas : A Sample Preparation-Coupled Laser Spectrometer System for Simultaneous High-Precision in Situ Analysis of δ13C and δ2H from Ambient Air Methane

Rennick, Chris ; Arnold, Tim LU orcid ; Safi, Emmal ; Drinkwater, Alice ; Dylag, Caroline ; Webber, Eric Mussell ; Hill-Pearce, Ruth ; Worton, David R. ; Bausi, Francesco and Lowry, Dave (2021) In Analytical Chemistry 93(29). p.10141-10151
Abstract

We present a new instrument, "Boreas", a cryogen-free methane (CH4) preconcentration system coupled to a dual-laser spectrometer for making simultaneous measurements of δ13C(CH4) and δ2H(CH4) in ambient air. Excluding isotope ratio scale uncertainty, we estimate a typical standard measurement uncertainty for an ambient air sample of 0.07‰ for δ13C(CH4) and 0.9‰ for δ2H(CH4), which are the lowest reported for a laser spectroscopy-based system and comparable to isotope ratio mass spectrometry. We trap CH4 (∼1.9 μmol mol-1) from ∼5 L of air onto the front end of a packed column, subsequently separating CH4 from interferences using a controlled temperature ramp with nitrogen (N2) as the carrier gas, before eluting CH4 at ∼550 μmol mol-1.... (More)

We present a new instrument, "Boreas", a cryogen-free methane (CH4) preconcentration system coupled to a dual-laser spectrometer for making simultaneous measurements of δ13C(CH4) and δ2H(CH4) in ambient air. Excluding isotope ratio scale uncertainty, we estimate a typical standard measurement uncertainty for an ambient air sample of 0.07‰ for δ13C(CH4) and 0.9‰ for δ2H(CH4), which are the lowest reported for a laser spectroscopy-based system and comparable to isotope ratio mass spectrometry. We trap CH4 (∼1.9 μmol mol-1) from ∼5 L of air onto the front end of a packed column, subsequently separating CH4 from interferences using a controlled temperature ramp with nitrogen (N2) as the carrier gas, before eluting CH4 at ∼550 μmol mol-1. This processed sample is then delivered to an infrared laser spectrometer for measuring the amount fractions of 12CH4, 13CH4, and 12CH3D isotopologues. We calibrate the instrument using a set of gravimetrically prepared amount fraction primary reference materials directly into the laser spectrometer that span a range of 500-626 μmol mol-1 (CH4 in N2) made from a single pure CH4 source that has been isotopically characterized for δ13C(CH4) by IRMS. Under the principle of identical treatment, a compressed ambient air sample is used as a working standard and measured between air samples, from which a final calibrated isotope ratio is calculated. Finally, we make automated measurements of both δ13C(CH4) and δ2H(CH4) in over 200 ambient air samples and demonstrate the application of Boreas for deployment to atmospheric monitoring sites.

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author
; ; ; ; ; ; ; ; and
publishing date
type
Contribution to journal
publication status
published
in
Analytical Chemistry
volume
93
issue
29
pages
11 pages
publisher
The American Chemical Society (ACS)
external identifiers
  • scopus:85111216019
ISSN
0003-2700
DOI
10.1021/acs.analchem.1c01103
language
English
LU publication?
no
additional info
Publisher Copyright: © 2021 American Chemical Society.
id
979cbc32-bbe3-4137-a234-95ac0ea7fe53
date added to LUP
2024-10-24 09:29:52
date last changed
2025-01-02 16:28:57
@article{979cbc32-bbe3-4137-a234-95ac0ea7fe53,
  abstract     = {{<p>We present a new instrument, "Boreas", a cryogen-free methane (CH4) preconcentration system coupled to a dual-laser spectrometer for making simultaneous measurements of δ13C(CH4) and δ2H(CH4) in ambient air. Excluding isotope ratio scale uncertainty, we estimate a typical standard measurement uncertainty for an ambient air sample of 0.07‰ for δ13C(CH4) and 0.9‰ for δ2H(CH4), which are the lowest reported for a laser spectroscopy-based system and comparable to isotope ratio mass spectrometry. We trap CH4 (∼1.9 μmol mol-1) from ∼5 L of air onto the front end of a packed column, subsequently separating CH4 from interferences using a controlled temperature ramp with nitrogen (N2) as the carrier gas, before eluting CH4 at ∼550 μmol mol-1. This processed sample is then delivered to an infrared laser spectrometer for measuring the amount fractions of 12CH4, 13CH4, and 12CH3D isotopologues. We calibrate the instrument using a set of gravimetrically prepared amount fraction primary reference materials directly into the laser spectrometer that span a range of 500-626 μmol mol-1 (CH4 in N2) made from a single pure CH4 source that has been isotopically characterized for δ13C(CH4) by IRMS. Under the principle of identical treatment, a compressed ambient air sample is used as a working standard and measured between air samples, from which a final calibrated isotope ratio is calculated. Finally, we make automated measurements of both δ13C(CH4) and δ2H(CH4) in over 200 ambient air samples and demonstrate the application of Boreas for deployment to atmospheric monitoring sites.</p>}},
  author       = {{Rennick, Chris and Arnold, Tim and Safi, Emmal and Drinkwater, Alice and Dylag, Caroline and Webber, Eric Mussell and Hill-Pearce, Ruth and Worton, David R. and Bausi, Francesco and Lowry, Dave}},
  issn         = {{0003-2700}},
  language     = {{eng}},
  month        = {{07}},
  number       = {{29}},
  pages        = {{10141--10151}},
  publisher    = {{The American Chemical Society (ACS)}},
  series       = {{Analytical Chemistry}},
  title        = {{Boreas : A Sample Preparation-Coupled Laser Spectrometer System for Simultaneous High-Precision in Situ Analysis of δ<sup>13</sup>C and δ<sup>2</sup>H from Ambient Air Methane}},
  url          = {{http://dx.doi.org/10.1021/acs.analchem.1c01103}},
  doi          = {{10.1021/acs.analchem.1c01103}},
  volume       = {{93}},
  year         = {{2021}},
}