Ion Mobility Studies on the Negative Ion-Molecule Chemistry of Isoflurane and Enflurane

Ramón González-Méndez, Peter Watts, David C. Howse, Immacolata Procino, Henry McIntyre, Chris A. Mayhew

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11 Citations (Scopus)
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In the present work we present an investigation of the negative ion-molecule chemistry of the anaesthetics isoflurane, ISOF, and enflurane, ENF, in an ion mobility spectrometry/mass spectrometry (IMS/MS), in both air and nitrogen. Hexachloroethane (HCE) was introduced in both air and nitrogen to produce Cl as a reactant ion. This study was undertaken owing to uncertainties in the chemical processes, which lead to the cluster ions reported in other work (Eiceman et al. Anal. Chem. 61, 1093–1099, 1). In particular for ISOF the product ion observed was ISOF.Cl, and it was suggested that the Cl was formed by dissociative electron attachment (DEA) although there was mention of a chlorine containing contaminant. We show in this study that ISOF and ENF do not produce Cl in an IMS system either by capture of free electrons or reaction with O2 . This demonstrates that the Cl containing ions, reported in the earlier study, must have been the result of a chlorine containing contaminant as suggested. The failure of ISOF and ENF to undergo DEA was initially surprising given the high calculated electron affinities, but further calculations showed that this was a result of the large positive vertical attachment energies (VAEs). This experimental work has been supported by electronic structure calculations at the B3LYP level, and is consistent with those obtained in a crossed electron-molecular beam two sector field mass spectrometer. An unusual observation is that the monomer complexes of ISOF and ENF with O2 are relatively unstable compared with the dimer complexes. [Figure not available: see fulltext.]

Original languageEnglish
Pages (from-to)939-946
Number of pages8
JournalJournal of the American Society for Mass Spectrometry
Issue number5
Early online date21 Feb 2017
Publication statusPublished - 1 May 2017
Externally publishedYes

Bibliographical note

The final publication is available at via


  • Enflurane
  • IMS-MS
  • Ion mobility spectrometry
  • Ion-molecule reactions
  • Isoflurane

ASJC Scopus subject areas

  • Structural Biology
  • Spectroscopy


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