title: Ion Mobility Studies on the Negative Ion-Molecule Chemistry of Isoflurane and Enflurane.
abstract: 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. Graphical Abstract ᅟ.
authors.affiliation: School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK. R.GonzalezMendez@bham.ac.uk.
authors.forename: Ramón
authors.identifier: 0000-0002-6481-456X
authors.initials: R
authors.lastname: González-Méndez
authors.affiliation: School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
authors.forename: Peter
authors.initials: P
authors.lastname: Watts
authors.affiliation: School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
authors.forename: David C
authors.initials: DC
authors.lastname: Howse
authors.affiliation: Smiths Detection, Century House, Maylands Avenue, Hemel Hempstead, Hertfordshire, HP2 7DE, UK.
authors.forename: Immacolata
authors.initials: I
authors.lastname: Procino
authors.affiliation: Smiths Detection, Century House, Maylands Avenue, Hemel Hempstead, Hertfordshire, HP2 7DE, UK.
authors.forename: Henry
authors.initials: H
authors.lastname: McIntyre
authors.affiliation: School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.|Institut für Atemgasanalytik, Leopold-Franzens-Universität Innsbruck, Rathausplatz 4, A-6850, Dornbirn, Austria.
authors.forename: Chris A
authors.initials: CA
authors.lastname: Mayhew
keywords: Enflurane; IMS-MS; Ion mobility spectrometry; Ion-molecule reactions; Isoflurane