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Development of PTR-MS selectivity for structural isomers: monoterpenes as a case study

Misztal, P.K.; Heal, M.R.; Nemitz, E.; Cape, J.N.. 2012 Development of PTR-MS selectivity for structural isomers: monoterpenes as a case study. International Journal of Mass Spectrometry, 310. 10-19. 10.1016/j.ijms.2011.11.001

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Abstract/Summary

Proton-Transfer-Reaction Mass Spectrometry (PTR-MS) is a very useful tool for high frequency detection and quantification of gas-phase volatile organic compounds (VOCs) but the soft ionization means it is difficult to discriminate structural isomers. For example, to date it has only been possible to measure the sum of monoterpene concentrations, which have been monitored most commonly at m/z 81 and 137 at a constant drift voltage and pressure. We show here that PTR-MS is capable of discriminating individual monoterpenes when operating in the alternating drift voltage (AD) mode. The approach is based on the principle that slightly different energies are required for the fragmentation/clustering of a given monoterpene, so in AD mode each monoterpene has different time points for fragmentation. Therefore from a fragmentation analysis of background-subtracted standards it is possible to calculate the percentage of each monoterpene in an absolute concentration of their sum. Although monoterpenes have been chosen as an example, the method is likely to be effective for other structural isomeric species such as the sesquiterpenes or methyl vinyl ketone/methacrolein (MVK/MACR).

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.1016/j.ijms.2011.11.001
Programmes: CEH Topics & Objectives 2009 - 2012 > Biogeochemistry > BGC Topic 1 - Monitoring and Interpretation of Biogeochemical and Climate Changes
CEH Sections: Billett (to November 2013)
ISSN: 1387-3806
Additional Keywords: fragmentation, scanning voltage, positive matrix factorization, terpene
NORA Subject Terms: Atmospheric Sciences
Chemistry
Date made live: 26 Apr 2012 11:04
URI: http://nora.nerc.ac.uk/id/eprint/17314

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