| A study of oleic acid and 2,4-DHB acid aerosols using an IR-VUV-ITMS: insights into the strengths and weaknesses of the technique. | |
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MedLine Citation:
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PMID: 19727503 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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An investigation of oleic acid and 2,4-dihydroxybenzoic (DHB) acid aerosols was carried out using an aerosol mass spectrometer with pulsed lasers for vaporization and ionization and an ion trap for mass analysis. The extent of ion fragmentation was studied as a function of both vaporization energy and ionization wavelength. Low CO2 laser energies in the vaporization stage and near-threshold single photon ionization resulted in the least fragmented mass spectra. For DHB, only the molecular ion was observed, but for oleic acid fragmentation could not be eliminated. Tandem MS of the main fragment peak from oleic acid was carried out and provided a tool for compound identification. Photoionization efficiency curves were also collected for both DHB and oleic acid and the appearance energies of both parent and fragment ions were measured. Evidence for fragmentation occurring post-ionization is given by the similar appearance energies for both the parent and fragment ions. The results from this study were compared with those from similar experiments undertaken with time-of-flight (TOF) mass analyzers. The degree of fragmentation in the ion trap was considerably higher than that seen with TOF systems, particularly for oleic acid. This was attributed to the long storage interval in the ion trap which allows time for metastable ions to decay. Differences in the degree of fragmentation between the ion trap and TOF studies also provided further evidence for fragmentation occurring post-ionization. For 2,4-dihydroxybenzoic acid, the long delay prior to mass analysis also allowed time for reactions with background gases, in this case water, to occur. |
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Authors:
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Sarah J Hanna; Pedro Campuzano-Jost; Emily A Simpson; Itamar Burak; Michael W Blades; John W Hepburn; Allan K Bertram |
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Publication Detail:
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Type: Evaluation Studies; Journal Article; Research Support, Non-U.S. Gov't Date: 2009-06-30 |
Journal Detail:
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Title: Physical chemistry chemical physics : PCCP Volume: 11 ISSN: 1463-9076 ISO Abbreviation: Phys Chem Chem Phys Publication Date: 2009 Sep |
Date Detail:
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Created Date: 2009-09-03 Completed Date: 2009-11-12 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 100888160 Medline TA: Phys Chem Chem Phys Country: England |
Other Details:
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Languages: eng Pagination: 7963-75 Citation Subset: IM |
Affiliation:
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Department of Chemistry, University of British Columbia, Vancouver, Canada BC V6T 1Z1. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Aerosols
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analysis,
chemistry* Atmosphere / analysis, chemistry* Benzophenones / analysis, chemistry* Environmental Monitoring / methods Gases / analysis, chemistry Oleic Acid / analysis, chemistry* Particle Size Particulate Matter / analysis, chemistry* Spectrometry, Mass, Electrospray Ionization / methods* Spectrophotometry, Ultraviolet / methods* |
| Chemical | |
Reg. No./Substance:
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0/Aerosols; 0/Benzophenones; 0/Gases; 0/Particulate Matter; 112-80-1/Oleic Acid; 131-56-6/2,4-dihydroxybenzophenone |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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