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

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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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