Effect of positive ion/molecule reactions on the response of the electron capture detector to anthracene

Grimsrud, E. P.

doi:10.1021/ac00275a011

Cited by 15 publications

(7 citation statements)

References 31 publications

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“…It is thought that the beneficial effects on ECD responses to various molecules described in the previous results section were caused by two different modifications of Reactions (3)(4)(5)(6)(7)(8)(9). The first one, positive ion stabilization by (CH&N is caused simply by making the terminal positive ions, P', more stable and unreactive so their reaction with analyte in Reaction (4), does not occur.…”

Section: Kinetic Model For Ecd Responses Of Low Ea Resonance Capturementioning

confidence: 93%

“…Reaction (4) is a positive ionmolecule reaction of the normally-present positive ions [4] with the analyte molecule, A. Reaction (5) is reversible resonance electron capture by A.…”

Section: Kinetic Model For Ecd Responses Of Low Ea Resonance Capturementioning

confidence: 99%

“…Baseline frequency as a function of the concentration of various monochlorohydrocarbons in nitrogen detector gas at 250%. Trimethylamine (TMA) was also added when desired to the detector gas dilution sphere for the purpose of stabilizing positive ion chemistry [4,5]. The addition of TMA causes a small improvement (decrease) in the ECD baseline frequency and between concentration levels of about 20to 200 ppm, has a constant effect on ECD responses.…”

Section: K E + a And Ak-1mentioning

confidence: 99%

“…The reactions which are thought to have the greatest effect on electron density are the following: (3) is the ionization of the detector gas by beta radiation to form positive ions, P+,and electrons, e.The rate of this process, S, is constant. Reaction (4) is a positive ionmolecule reaction of the normally-present positive ions [4] with the analyte molecule, A. Reaction (5) is reversible resonance electron capture by A.…”

Section: Kinetic Model For Ecd Responses Of Low Ea Resonance Capturementioning

confidence: 99%

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Electron capture detector response to low electron affinity aromatic hydrocarbons using positive ion stabilization and alkyl chloride sensitization

Valkenburg

Knighton

Grimsrud

1986

J. High Resol. Chromatogr.

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SummaryThe electron capture detector (ECD) response to numerous aromatic hydrocarbons of low electron affinity (EA) is shown to be detrimentally affected by two processes which compete with and typically overwhelm the electron capture reactions of these molecules. It is shown that the effects of these two undesired reactions can be eliminated by the permanent addition of trimethylamine and one of several alkyl monochlorides to the detector make-up gas. These modifications of the detector gas result in greatly increased sensitivity, increased linearity, and increased reproducibility of response. A kinetic model for the ECD responses of low EA resonance capture molecules is developed which appears to explain these improvements.

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Section: Kinetic Model For Ecd Responses Of Low Ea Resonance Capturementioning

confidence: 93%

“…Reaction (4) is a positive ionmolecule reaction of the normally-present positive ions [4] with the analyte molecule, A. Reaction (5) is reversible resonance electron capture by A.…”

Section: Kinetic Model For Ecd Responses Of Low Ea Resonance Capturementioning

confidence: 99%

Section: K E + a And Ak-1mentioning

confidence: 99%

Section: Kinetic Model For Ecd Responses Of Low Ea Resonance Capturementioning

confidence: 99%

See 2 more Smart Citations

Electron capture detector response to low electron affinity aromatic hydrocarbons using positive ion stabilization and alkyl chloride sensitization

Valkenburg

Knighton

Grimsrud

1986

J. High Resol. Chromatogr.

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“…Reactions with positive ions should not be competitive with fast electron capture since they occur with maximum rate constants of about 1 X 10"9 cm3 s'1 (11). If desired, however, positive ion chemistry can be quenched by doping the carrier gas with strong gas-phase bases such as trimethylor triethylamine (12,13). These dopants form unusually stable and unreactive positive ions and do not attach electrons.…”

mentioning

confidence: 99%

Effect of pulse parameters on analyses by tandem-cell gas-phase coulometry

Warden¹,

Crawford²,

Knighton³

et al. 1985

Anal. Chem.

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The analyses of several halogenated methanes by gas-phase coulometry (GPC) and two Identical tandem electron capture detectors (ECD) are reported. A dependence of the GPC results on pulse frequency Is observed which Is not accommodated by present theory of the method. The effects of other variations of the pulsing parameters are also reported. Several potential explanations for these unexpected results are considered. An Initially favored candidate, that due to the collection of anions at the anode, is not supported here by experiments designed to test It. It Is concluded that the method of GPC, as It presently exists, probably Is not yet one which offers an Independent means for hlgh-accuracy determinations. Because of the unexplained dependence of the GPC result on pulse frequency, calibration of the GPC response against reliable reference standards Is presently necessary If accuracies of a few percent or better are sought.The concept of gas-phase coulometry (GPC) by the electron capture detector (ECD) for gas chromatography (GC) was first described by Lovelock, Maggs, and Adlard (1) in 1971. This article caused considerable interest in the field of trace organic analysis because, in theory, this method offered a convenient means for the quantitative analysis of certain substances at

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Ionization dynamics within the high pressure electron capture mass spectrometer; the unusual spectra of derivatized polycyclic aromatic amines and perchlorinated unsaturated hydrocarbons

Sears

Campbell

Grimsrud

1987

Biol. Mass Spectrom.

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A kinetic model for chemical events occurring within the high pressure electron capture mass spectrometer (HPECMS) ion source is developed which includes four different pathways by which unconventional negative ions can be produced. These routes to unusual ions include reactions of gas phase free radicals, surfaceassisted reactions, ion-electron and ion-ion recombination reactions, and ion-wall neutralization. The model developed here provides a diagnostic tool useful for the elucidation of unusual HPEC spectra. Such spectra for two environmentally important classes of compounds are explained by use of the model. These compound classes include the trifluoroacetic derivatives of polycyclic aromatic amines, which have been shown to be present in materials derived from liquified coal, and the derivatives of hexachlorocyclopentadiene, which are used as pesticides. It is shown in this study that several processes, in addition to electron capture, can be operative in the typical HPECMS ion source, and that these processes can be used advantageously for the generation of informative and sensitive mass spectral signals.

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Effect of positive ion/molecule reactions on the response of the electron capture detector to anthracene

Cited by 15 publications

References 31 publications

Electron capture detector response to low electron affinity aromatic hydrocarbons using positive ion stabilization and alkyl chloride sensitization

Electron capture detector response to low electron affinity aromatic hydrocarbons using positive ion stabilization and alkyl chloride sensitization

Effect of pulse parameters on analyses by tandem-cell gas-phase coulometry

Ionization dynamics within the high pressure electron capture mass spectrometer; the unusual spectra of derivatized polycyclic aromatic amines and perchlorinated unsaturated hydrocarbons

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