Processing of CO2 samples collected using zeolite molecular sieve for 14C analysis at the NERC radiocarbon facility (East Kilbride, UK)

Garnett, M.H. and Murray, C. (2013) Processing of CO2 samples collected using zeolite molecular sieve for 14C analysis at the NERC radiocarbon facility (East Kilbride, UK). Radiocarbon, 55(2-3), pp. 410-415. (doi:10.2458/azu_js_rc.55.16058)

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Abstract

Cartridges containing a zeolite molecular sieve are used for the field collection of CO2 from a variety of environments (e.g. atmosphere, soil respiration, evasion from surface waters) for accelerator mass spectrometry (AMS) radiocarbon analysis by the NERC Radiocarbon Facility. Previously, sample CO2 was recovered from the sieves by heating under vacuum prior to cryogenic purification and graphitization. An additional heating and evacuation stage was used to prepare the cartridge for the next sample. We have recently developed an alternative method using heating and purging with nitrogen gas to remove sample CO2 from the molecular sieve. An infrared gas analyzer (IRGA) is used to continuously monitor CO2 content in the purge gas. The preparation of the molecular sieve cartridge for the next use is performed simultaneously and the IRGA reading is used to verify that all sample CO2 has been removed from the sieve, ensuring insignificant carryover of CO2 into the next sample. We present the results of a suite of standards of distinctly different 14C and stable-carbon isotope composition, which we used to confirm the reliability of the new procedure. The new method has considerably reduced the time required to process a single sample from at least 2 hr to less than 40 min, and reduced the minimum sample size by 50%.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Murray, Mr Callum and Garnett, Dr Mark
Authors: Garnett, M.H., and Murray, C.
College/School:College of Science and Engineering > Scottish Universities Environmental Research Centre
Journal Name:Radiocarbon
Publisher:University of Arizona
ISSN:0033-8222
ISSN (Online):0033-8222
Copyright Holders:Copyright © 2013 Arizona Board of Regents on behalf of the University of Arizona
First Published:First published in Radiocarbon 55(2-3):410-415
Publisher Policy:Reproduced under a Creative Commons License

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