Coupled polymer-membrane equilibration and cavity ring-down spectrometry for the highly sensitive determination of dissolved methane in environmental waters

Munksgaard, Niels C., and Nelson, Paul N. (2020) Coupled polymer-membrane equilibration and cavity ring-down spectrometry for the highly sensitive determination of dissolved methane in environmental waters. Analytical Letters. (In Press)

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Abstract

High sensitivity field-based analysis of dissolved methane in surface water and groundwater is needed to monitor the environmental impacts of natural gas-field development and understand microbial carbon cycling in water bodies. A new analytical technique using a polymer membrane contactor coupled to a laser-based cavity ringdown spectrometer was developed and tested. By recirculating a water sample for approximately 10 mins, equilibrium was established between dissolved methane in the sample and methane in the measured gas phase according to Henry’s Law. The performance of the system was investigated by replicate analyses of several different water samples, spike recovery tests, comparison to analysis by headspace gas chromatography, and consideration of memory effects. The technique provided an adequate detection limit for the determination of natural background concentrations of methane in environmental waters and was approximately 28 times more sensitive than analysis by gas chromatography. The system is field-capable, simple to operate and calibrate, and takes advantage of the low-drift characteristics of the cavity ring-down spectrometer.

Item ID: 63229
Item Type: Article (Research - C1)
ISSN: 1532-236X
Keywords: carbon dioxide, Henry’s Law, laser spectroscopy, membrane contactor, methane
Copyright Information: © 2020 Taylor & Francis Group, LLC
Date Deposited: 22 May 2020 00:17
FoR Codes: 03 CHEMICAL SCIENCES > 0301 Analytical Chemistry > 030101 Analytical Spectrometry @ 30%
03 CHEMICAL SCIENCES > 0301 Analytical Chemistry > 030108 Separation Science @ 30%
05 ENVIRONMENTAL SCIENCES > 0502 Environmental Science and Management > 050206 Environmental Monitoring @ 40%
SEO Codes: 96 ENVIRONMENT > 9611 Physical and Chemical Conditions of Water > 961103 Physical and Chemical Conditions of Water in Fresh, Ground and Surface Water Environments (excl. Urban and @ 40%
96 ENVIRONMENT > 9602 Atmosphere and Weather > 960201 Atmospheric Composition (incl. Greenhouse Gas Inventory) @ 40%
85 ENERGY > 8502 Mining and Extraction of Energy Resources > 850203 Oil and Gas Extraction @ 20%
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