Quantification of oxygenated volatile organic compounds in seawater by membrane inlet-proton transfer reaction/mass spectrometry

Rachael Beale, Peter S. Liss, Joanna L. Dixon, Philip D. Nightingale

Research output: Contribution to journalArticlepeer-review

37 Citations (Scopus)

Abstract

The role of the ocean in the cycling of Oxygenated Volatile Organic Compounds (OVOCs) remains largely unanswered due to a paucity of datasets. We describe the method development of a Membrane Inlet - Proton Transfer Reaction/Mass Spectrometer (MI-PTR/MS) as an efficient method of analysing methanol, acetaldehyde and acetone in seawater. Validation of the technique with water standards show that the optimised responses are linear and reproducible. Limits of detection are 27 nM for methanol, 0.7 nM for acetaldehyde and 0.3 nM for acetone. Acetone and acetaldehyde concentrations generated by MI-PTR/MS are compared to a second, independent method based on purge and trap - gas chromatography/flame ionisation detection (P&T-GC/FID) and show excellent agreement. Chromatographic separation of isomeric species acetone and propanal permits correction to mass 59 signal generated by the PTR/MS and overcomes a known uncertainty in reporting acetone concentrations via mass spectrometry. A third bioassay technique using radiolabelled acetone further supported the result generated by this method. We present the development and optimisation of the MI-PTR/MS technique as a reliable and convenient tool for analysing seawater samples for these trace gases. We compare this method with other analytical techniques and discuss its potential use in improving the current understanding of the cycling of oceanic OVOCs.
Original languageEnglish
Pages (from-to)128–134
Number of pages7
JournalAnalytica Chimica Acta
Volume706
Issue number1
Early online date22 Aug 2011
DOIs
Publication statusPublished - 7 Nov 2011

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