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www.atmos-meas-tech-discuss.net/3/2433/2010/
doi:10.5194/amtd-3-2433-2010
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under the Creative Commons Attribution 3.0 License.
Continuous-flow isotope ratio mass spectrometry method for carbon and hydrogen isotope measurements on atmospheric methane
Institute for Marine and Atmospheric research Utrecht, Utrecht University, Utrecht, The Netherlands
Abstract. We describe a continuous-flow isotope ratio mass spectrometry (CF-IRMS) technique for high-precision δD and δ13C measurements of atmospheric methane on 40 mL air samples. CH4 is separated from other air components by utilizing purely physical processes based on temperature, time and mechanical valve switching. Chemical agents are avoided. Trace amounts of interfering compounds can be separated by gas chromatography after pre-concentration of the CH4 sample. The fully purified sample is then either combusted to CO2 or pyrolyzed to H2 for stable isotope measurement. Apart from connecting samples and refilling liquid nitrogen as coolant the system is fully automated and allows an unobserved, continuous analysis of samples. The analytical system has been used for analysis of air samples with CH4 mixing ratios between ~100 and ~10000 ppb, for higher mixing ratios samples usually have to be diluted.
Discussion Paper (PDF, 1737 KB) Interactive Discussion (Closed, 6 Comments) Final Revised Paper (AMT)
Notice on Discussion StatusCitation: Brass, M. and Röckmann, T.: Continuous-flow isotope ratio mass spectrometry method for carbon and hydrogen isotope measurements on atmospheric methane, Atmos. Meas. Tech. Discuss., 3, 2433-2476, doi:10.5194/amtd-3-2433-2010, 2010. Bibtex EndNote Reference Manager XML
