Gas phase ion chemistry of coumarins

Ab initio calculations used to justify negative chemical ionization trends

Kwenga F. Sichilongo, Victor O. Jaoko, Foster Mbaiwa, Ishmael B. Masesane

    Research output: Contribution to journalArticle

    Abstract

    The gas phase ion chemistry of coumarins using electron ionization (EI), positive chemical ionization (PCI) and negative chemical ionization (NCI) in a time of flight and quadrupole mass spectrometer (qMS) coupled to a gas chromatograph is outlined. The observations in NCI mode were complimented with Ab initio calculations. This was because NCI gave enhanced signals in contrast to EI and PCI and therefore could serve as a potential ionization method for quantitative analysis. For the two classes of analytes that were examined here, i.e. methyl and acetyl coumarin derivatives, experimental data showed that the methyl derivatives underwent dissociative electron capture to produce ions of the type [M-H]- while the acetyl derivatives underwent resonance electron capture to produce ions of the type M-. The M- type of ions were more intense than the earlier. Ab initio calculations showed higher electron affinities in the acetyl than the methyl derivatives.

    Original languageEnglish
    Pages (from-to)473-484
    Number of pages12
    JournalBulletin of the Chemical Society of Ethiopia
    Volume29
    Issue number3
    DOIs
    Publication statusPublished - 2015

    Fingerprint

    Coumarins
    Ionization
    Gases
    Ions
    Derivatives
    Electrons
    Electron resonance
    Electron affinity
    Ionization potential
    Mass spectrometers
    Chemical analysis

    All Science Journal Classification (ASJC) codes

    • Chemistry(all)

    Cite this

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    abstract = "The gas phase ion chemistry of coumarins using electron ionization (EI), positive chemical ionization (PCI) and negative chemical ionization (NCI) in a time of flight and quadrupole mass spectrometer (qMS) coupled to a gas chromatograph is outlined. The observations in NCI mode were complimented with Ab initio calculations. This was because NCI gave enhanced signals in contrast to EI and PCI and therefore could serve as a potential ionization method for quantitative analysis. For the two classes of analytes that were examined here, i.e. methyl and acetyl coumarin derivatives, experimental data showed that the methyl derivatives underwent dissociative electron capture to produce ions of the type [M-H]- while the acetyl derivatives underwent resonance electron capture to produce ions of the type M-. The M- type of ions were more intense than the earlier. Ab initio calculations showed higher electron affinities in the acetyl than the methyl derivatives.",
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    Gas phase ion chemistry of coumarins : Ab initio calculations used to justify negative chemical ionization trends. / Sichilongo, Kwenga F.; Jaoko, Victor O.; Mbaiwa, Foster; Masesane, Ishmael B.

    In: Bulletin of the Chemical Society of Ethiopia, Vol. 29, No. 3, 2015, p. 473-484.

    Research output: Contribution to journalArticle

    TY - JOUR

    T1 - Gas phase ion chemistry of coumarins

    T2 - Ab initio calculations used to justify negative chemical ionization trends

    AU - Sichilongo, Kwenga F.

    AU - Jaoko, Victor O.

    AU - Mbaiwa, Foster

    AU - Masesane, Ishmael B.

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    AB - The gas phase ion chemistry of coumarins using electron ionization (EI), positive chemical ionization (PCI) and negative chemical ionization (NCI) in a time of flight and quadrupole mass spectrometer (qMS) coupled to a gas chromatograph is outlined. The observations in NCI mode were complimented with Ab initio calculations. This was because NCI gave enhanced signals in contrast to EI and PCI and therefore could serve as a potential ionization method for quantitative analysis. For the two classes of analytes that were examined here, i.e. methyl and acetyl coumarin derivatives, experimental data showed that the methyl derivatives underwent dissociative electron capture to produce ions of the type [M-H]- while the acetyl derivatives underwent resonance electron capture to produce ions of the type M-. The M- type of ions were more intense than the earlier. Ab initio calculations showed higher electron affinities in the acetyl than the methyl derivatives.

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