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  • Analytical Chemistry and Spectroscopy  (12)
  • 1
    Electronic Resource
    Electronic Resource
    A sensitive and specific stable isotope assay for warfarin and its metabolites (1983)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1983), S. 395-398 
    Details
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A capillary gas chromatographic mass spectrometric method for the quantification of warfarin and its known metabolites from microsomal incubations is described. Deuterium labelled 4′, 6-, 7- and 8-hydroxy warfarins are used as internal standards and the method has detection limits of 1 ng ml-1 with 20 ng ml-1 being the lower limit for accurate quantification.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200100702
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  • 2
    Electronic Resource
    Electronic Resource
    A site specific rearrangement in electron capture negative ion CI mass spectrometry of pentafluoropropionyl derivatives of some β-hydroxyamines (1984)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 11 (1984), S. 177-181 
    Details
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This study reports a rearrangement process observed in electron capture negative ion chemical ionization mass spectrometry of pentafluoropropionate and heptafluorobutyrate derivatives of some β-hydroxylated amines. The pentafluoropropionate derivatives of a number of these substituted amines yield a prominent anion of mass 145 (195 in the corresponding heptafluorobutyrate derivatives). In the pentafluoropropionate derivatives of ethanolamine and β-hydroxyphenethylamine this anion was quantitatively displaced to m/z 146 when the γ-hydrogen (relative to the derivatized hydroxyl group) was substituted by deuterium. We postulate an initial 6-membered transition state to produce a pentafluoropropionic acid anion (not observed) which then eliminates either a hydrogen atom to give m/z 163 or a fluorine atom to give m/z 145. The former remains at mass 163 in the γ-deuterated compounds examined. The proposed rearrangement is the negative ion analogue of the McLafferty rearrangement process of positive ion electron impact mass spectrometry. However, the negative ion rearrangement is not as general as its positive ion electron impact counterpart because the former is critically dependent upon the substitution present on the α and β carbon and nitrogen atoms, respectively, of the β-hydroxyamine-PFP (or HFB) derivatives. In this regard we examined the effects on m/z 145 anion formation of methyl substitution on the nitrogen and α and β carbon atoms of these pentafluoropropionate derivatives. The results suggest that electron capture methane negative ion chemical ionization mass spectra of β-hydroxylated PFP derivatives could be used as diagnostic tool for structural assignments within this group of compounds.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200110408
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  • 3
    Electronic Resource
    Electronic Resource
    Positive and negative ion chemical ionization mass spectra of amino acid carboxy-n-butyl Ester N-Pentafluoropropionate Derivatives (1984)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 11 (1984), S. 223-229 
    Details
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The positive and negative chemical ionization mass spectra of 29 amino acid carboxy-n-butyl ester N-(O,S)-Pentafluoropropionate derivatives hae been determined. The positive ion (PI) mass spectra conform to the expected fragmentation patterns for this amino acid derivative but their methane negative ion chemical ionization (NICI) mass spectra displayed marked differences between various amino acid classes and bvetween positional isomers within the same class. Isomeric butyric acid (α, β and γ) and tyrosine (o, m amd p-hydroxylation) derivatives all had remarkably difterent NICI mass spectra. Aliphatic amino acid CO2-n-butyl-N-PFP derivatives (except glycine) can be readily recognized by a characteristic fragmentation process corresponding to [M-H-C4CO2H]-. Deuterium labellung studies were used to delineate some of the major NICI fragmentation processes. While the PICI mass spectra all gave comparable detection responses differences were observed with various amino acids when operating in the NICI mode. The order of sensitivity of detection for six representative amino acid-carboxy-n-butyl-N-PFP derivatives were: hydroxyproline 〉 lysine 〉 cysteine 〉 glycine=leucine=methionine in the ratio of 100:20:7:1. In PICI mass spectrometry derivatized leucine yielded a response 25 times less than its NICI mass spectrometric value.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200110506
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  • 4
    Electronic Resource
    Electronic Resource
    Electron impact mass spectra of permethylated N-methyl,N-phenyl(glucopyranosyl-1-deoxyglucitol-1-yl)amines (1984)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 19 (1984), S. 518-519 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210191013
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  • 5
    Electronic Resource
    Electronic Resource
    Chemical ionization mass spectrometric characteristics of morphine alkaloids (1985)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 20 (1985), S. 511-514 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The ion-molecular reaction behavior of ten morphine alkaloids with several commonly used reagent gases are studied under chemical ionization mass spectrometry conditions. These studies emphasize the correlation of the structural characteristics of the 10 alkaloids with the following four mass spectrometric parameters: (i) mass shifts of the protonated ion as a result of replacing ammonia with deuterated ammonia as the reagent gas, (ii) relative tendencies of the adduct ion and the protonated ion to lose molecules of water, (iii) relative intensity ratio of the adduct ion and the protonated ion and (iv) tendency of a compound to undergo a reduction reaction.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210200806
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  • 6
    Electronic Resource
    Electronic Resource
    Further studies on a site-specific hydrogen transfer observed in electron capture negative ion chemical ionization mass spectrometry of hydroxyamine pentafluoropropionate derivatives (1985)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 20 (1985), S. 595-599 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Further studies have demonstrated that the site-specific hydrogen transfer process involved in the formation of the m/z 145 anion of β-hydroxyamine pentafluoropropionate (PFP) derivatives observed under electron capture negative ion chemical ionization conditions occurs when the two functional groups are separated by up to five carbon atoms. Deuterium labelling has established that the site specificity, transfer of a hydrogen atom from the carbon adjacent to nitrogen to the OPFP group, is maintained in 4-amino-butan-1-ol-N, O-(PFP)2. The corresponding PFP derivatives of the N-methylaminoalkanol-(PFP)2 derivatives lack the m/z 145 species with m/z 163, [OPFP]- being the base anion. Substitution of alkyl groups on the carbon adjacent to oxygen results in a diminution of the ion intensity at m/z 145. with a marked increase in the intensity of m/z 144. The formation of the m/z 145 and 144 anions to proposed to proceed through the intervention of a fluoride ion-molecule complex as outlined in Scheme 1 with the product ion distribution dependent on which of the two pathways is preferred.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210201002
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  • 7
    Electronic Resource
    Electronic Resource
    Selected ion monitoring mass spectrometry: Parameters affecting quantitative determination (1985)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 12 (1985), S. 633-637 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Instrumental parameters and possible correction procedures for hydrogen-transfer phenomena are studied, with emphasis on the improvement of quantitative measurements in selected ion monitoring mass spectrometry. The intensity ratio of the m/z 387 and 386 ions, derived from cholesterol, are measured by an HP-5995 mass spectrometer using different parameters, including calibration peak width, mass filter window size and ion monitoring dwell time. The intrinsic ratio of these two ions is calculated with a correction procedure accounting for the [M—H]+ and [M—2H]+ hydrogen-transfer phenomena.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200121102
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  • 8
    Electronic Resource
    Electronic Resource
    Direct mass spectrometric determination of 13C enrichment of organic compounds (1985)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 12 (1985), S. 638-642 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A direct mass spectrometric measurement method is developed for the determination of 13C enrichment and chemical purity of a labelled compound. The labelled compound is mixed with various amounts of unlabelled analogue to provide a series of mixtures containing different but comparable quantities of labelled and unlabelled species. Intensity ratios of selected isotopically anologous ions from these two species are determined using selected ion monitoring. Equations are established to relate measured intensity ratios to sample mixture weight ratios, chemical purities of the labelled and unlabelled compounds, ion composition and isotopic abundance of the enriched and unenriched carbons, A non-linear regression procedure, based on the measured intensity ratio, the mixture weight ratio and the known chemical purity of the unlabelled compound, is used to resolve the chemical purity and the isotopic abundance yielding results with standard errors of 1.0 and 0.4%, respectively. This procedure is suitable for compounds labelled with more than 60% of an isotope.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200121103
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  • 9
    Electronic Resource
    Electronic Resource
    Analysis of the constituents of Piper methysticum by gas chromatography methane chemical ionization mass spectrometry. New constituents of kava resin (1986)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 13 (1986), S. 305-313 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Methane chemical ionization mass spectrometry has been used to investigate the components of kava resin prepared by solvent extraction of commercial Piper methysticum Forst. All the known constitutents of this resin were identified together with several new compounds which of formally result from decarboxylation of the 4-methoxy-2-pyrone ring system in the known compounds. Chemical ionization mass spectrometry is a useful probe for the identification of these compounds because all gave easily recognized protonated molecular ions and the fragmentation patterns were related to molecular structure. Using this technique, the steam distillation products of commercial P. methysticum were identified, as was the product distribution from base hydrolysis of the known kava pyrone, yangonin.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200130608
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  • 10
    Electronic Resource
    Electronic Resource
    Determination of polycyclic aromatic hydrocarbons in coal fly ash using gas chromatography/negative ion chemical ionization mass spectrometry (1986)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 13 (1986), S. 95-104 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This study reports studies using electron capture negative ion chemical ionization gas chromatography/mass spectrometry (EC-NICI GC/MS) of 21 polycyclic aromatic hydrocaroon (PAH) compounds. The selectivity and sensitivity of these compounds are shown here to be highly dependent on ion source temperature and pressure. Changes in selectivity arise from variations in instrumental and can be largely explained by the competitive formation processes of [M]-. and [M—H]- ions. The formation of the adduct ion, [M + 15]-, previously attributed to [M + CH3]-, is shown here by using perdeuterated PAH analogues to be a [M + O — H]- ion. For fluorene and acenaphthene, abundant [M + 14]- and [M + 13]- ions can be similarly rationalized to be [M + O — 2H]- and [M + O — 3H]-. The NICI mass spectrum of (2H10)acenaphthene demonstrates that ring proton losses most likely occur. This study also indicates that there is a strong correlation between the NICI response factor and the reported carcinogenic activity of PAHs in the literature. In addition, this work assesses the viability of NICI GC/MS as an analytical technique for determining PAHs in fly ash with minimum sample pretreatment.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200130209
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