Fast determination of methyl chloride and methyl bromide emissions from dried plant matter and soil samples using HS-SPME and GC-MS: method and first results
Noureddine Yassaa A C , Asher Wishkerman B , Frank Keppler B and Jonathan Williams BA Faculty of Chemistry, University of Sciences and Technology Houari Boumediene, B.P. 32 El-Alia, Bab-Ezzouar, 16111 Algiers, Algeria.
B Air Chemistry Department, Max-Planck Institute for Chemistry, J.J. Becher Weg 27, D-55020 Mainz, Germany.
C Corresponding author. Email: n_yassaa@yahoo.fr
Environmental Chemistry 6(4) 311-318 https://doi.org/10.1071/EN09034
Submitted: 17 March 2009 Accepted: 19 June 2009 Published: 25 August 2009
Environmental context. Headspace solid-phase microextraction (HS-SPME) and analysis by gas chromatography–mass spectrometry (GC/MS) system has been employed for quantifying the emissions of methyl chloride (CH3Cl) and methyl bromide (CH3Br) from plants and soils. Compared with more commonly used techniques, HS-SPME coupled to GC/MS is simple, fast, sensitive, economical and non-destructive, with potential for laboratory-based and field studies.
Abstract. Headspace solid-phase microextraction (HS-SPME) and gas chromatography–mass spectrometry (GC/MS) system have been employed for quantifying the emissions of methyl chloride (CH3Cl) and methyl bromide (CH3Br) from plants and soils. Seven SPME fibre coatings including 75 μm Carboxen-polydimethylsiloxane (CAR-PDMS), 85 μm Carboxen-PDMS (CAR-PDMS), 50/30 μm divinylbenzene-CAR-PDMS (DVB-CAR-PDMS), 65 μm DVB-PDMS, 65 μm carbowax-DVB (CW-DVB), 30 μm PDMS (PDMS) and 100 μm PDMS, were tested by comparing their sampling efficiencies towards CH3Cl and CH3Br. Key parameters such as extraction time, desorption temperature and time were all optimised in this work. The optimum conditions were found with CAR-PDMS 75 μm as an SPME fibre coating, a 1-min sampling time, a 50°C incubation temperature and a 2-min desorption time and a 250°C desorption temperature. These conditions were used for the determination of CH3Cl and CH3Br emission rates from different plant species as well as soil samples. Compared with more commonly used techniques, HS-SPME coupled to GC/MS is simple, fast, sensitive, economical and non-destructive, with potential for laboratory-based and field studies.
Additional keywords: atmosphere, biogenic emissions, bromomethane, chloromethane, gas chromatography, mass spectrometry.
Acknowledgements
We are grateful to Bernhard Spettel and Andrey Cheburkin for instrumental and analytical support. Special thanks to Alke Jugold for collecting the soil samples from Botswana and the HALOPROC Project funded by the DFG.
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