| Autor: |
González-Méndez R; School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK. R.GonzalezMendez@bham.ac.uk., Watts P; School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK., Howse DC; School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK., Procino I; Smiths Detection, Century House, Maylands Avenue, Hemel Hempstead, Hertfordshire, HP2 7DE, UK., McIntyre H; Smiths Detection, Century House, Maylands Avenue, Hemel Hempstead, Hertfordshire, HP2 7DE, UK., Mayhew CA; 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. |
| Abstrakt: |
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 O 2 - . 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 O 2 - are relatively unstable compared with the dimer complexes. Graphical Abstract ᅟ. |
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