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Volume 53 (2005)
- Issue 6 Pages 305-
- Issue 5 Pages 241-
- Issue 4 Pages 183-
- Issue 3 Pages 89-
- Issue 2 Pages 53-
- Issue 1 Pages 1-
Volume 53, Issue 2
Displaying 1-3 of 3 articles from this issue
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REGULAR PAPER
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Susumu TAJIMA, Kanako MINEGISHI, Satoshi NAKAJIMA, Takae TAKEUCHI2005 Volume 53 Issue 2 Pages 53-59
Published: 2005
Released on J-STAGE: March 16, 2006
JOURNAL FREE ACCESSThe metastable ion dissociations of o-, m-, and p-acetylphenyl ions, CH3COC6H4+ (m/z 119), generated upon electron ionization from o-, m-, and p-diacetylbenzenes (CH3COC6H4COCH3, Mw : 162, 1-3), have been investigated by use of mass-analyzed ion kinetic energy (MIKE) spectrometry in conjunction with thermochemistry. All these m/z 119 ions, which are generated by the consecutive losses of CH3 and CO from 1+·-3+·, dissociate to only the ion at m/z 91 by the loss of CO. These suggest that in the CH3COC6H4+ ions, the CH3 migration from the acetyl group to the benzene ring occurs prior to the loss of CO. The amounts of the kinetic energy release (KER) accompanying with the dissociation of the m/z 119 ions from compounds 1-3 to m/z 91 ion were larger than those of the corresponding, respective methylbenzoyl ions. In the m-, and p-CH3COC6H4+ ions, the charge migrates from the incipient charge site to the ortho position via the so-called hydrogen “ring-walk.” Then CH3 migrates from the acetyl group to the charge site at the ortho position in the benzene ring prior to the loss of CO. A part of the m/z 91 ions from o-, m-, and p-acetylphenyl ions may be generated via the migration of CH3 to the incipient charge site, followed by the loss of CO.View full abstractDownload PDF (377K)
INTEGRATED PAPER
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Kenzo HIRAOKA2005 Volume 53 Issue 2 Pages 60-78
Published: 2005
Released on J-STAGE: March 16, 2006
JOURNAL FREE ACCESSNew ionization methods for GC/MS and LC/MS interface which have been developed in our laboratory will be described. The atmospheric pressure Penning ionization was developed for GC/MS interface. Its sensitivity was found to be as good as that of the electron impact ionization method. The laser spray developed for LC/MS interface, which can be regarded as the electric-field assisted MALDI, gave about one order of magnitude higher ion detection sensitivity than the conventional electrospray. In addition, laser spray can detect ions with different surface activities more non-selectively than electrospray.View full abstractDownload PDF (981K)
TECHNICAL REPORT
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Kiyoshi KAWABATA, Yoko URASAKI2005 Volume 53 Issue 2 Pages 79-87
Published: 2005
Released on J-STAGE: March 16, 2006
JOURNAL FREE ACCESSA method by liquid chromatography/atmospheric pressure chemical ionization tandem mass spectrometry (LC/APCI-MS/MS) for the quantitative determination of pravastatin and its main metabolite (R-416) in human plasma with a fully automated on-line solid-phase extraction (SPE) system, PROSPEKT-2TM was established. The method employed the direct on-line injection of human plasma into the PROSPEKT-2TM system for extraction of the analytes followed by column switching introduction of analytes to the LC/APCI-MS/MS system. The use of on-line SPE system resulted in reducing the sample preparation time and decreasing endogenous interfering substances in the extracts. The lower limit of quantification (LLOQ) for the assay was 0.1 ng/mL for pravastatin and R-416 on a 100 μL plasma sample. The calibration curves were linear for concentrations ranging from 0.1 to 100 ng/mL for both analytes. The intra- and inter-assay precisions were less than 4%. The method provides an automated sample analysis in a total cycle time of 6 min, allowing the analysis of many plasma samples to be conducted with increased throughput and improved robustness.View full abstractDownload PDF (1149K)
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