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  • Analytical Chemistry and Spectroscopy  (4)
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  • 1
    Electronic Resource
    Electronic Resource
    Automated metabolic profiling analysis of urinary steroids by a gas chromatography mass spectrometry data system (1983)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1983), S. 155-161 
    Details
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A computer system (MSSMET), using methylene unit retention indices for an off-line reverse library search analysis of selected ion chromatograms from gas-liquid chromatographic mass spectrometric data, has been applied for the qualitative and quantitative determination of daily variations in the excreted levels of urinary steroids of two individuals, using capillary column gas-liquid chromatography. Aliquots of 24 h urine collections and morning spot urine samples were examined. The daily excretion pattern of most of the major steroid metabolites was fairly consistent from day to day (i.e. 3α-hydroxy-5α-androstane-17-one, androsterone; 3α-hydroxy-5β-androstane-17-one, etiocheolanolone; 3α, 17α,21-trihydroxy-5β-pregnane-11,20-dione, THE; 3α,11β,17α,21-tetrahydroxy-5β-pregnane-20-one, THF; 3α,11β,17α,21-tetrahydroxy-5α-pregnane-20-one; allo-THF; 3α,17α,20α,21-tetrahydroxy-5β-pregnane-11-one, cortolone; 3α,17α,20β,21-tetrahydroxy-5β-pregnane-11-one, β-cortolone; 5β-pregnane-3α,11β,17α,20α,21-pentol, cortol; 5β-pregnane-3α,11β,17α,20β,21-pentol,β-cortol), while certain other steroid metabolites had a less consistent excretion pattern (3β-hydroxy-5-androstene-17-one, for example). Advantages and disadvantages of using capillary columns for the automated metabolic profile analysis of urinary steroids by reverse library search of selected mass chromatograms.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200100309
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Identification of 2-hydroxy fatty acids in complex mixtures of fatty acid methyl esters by mass chromatographyAbbreviations: Hydroxy fatty acids are identified by h preceding chain length. (1974)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 1 (1974), S. 10-14 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Repetitive mass spectrometric scanning of gas-liquid chromatographic effuents at short (6 to 15 s) intervals, with a digital computer for data acquisition, reduction and display, allows plots (mass chromatograms) to be made of the intensities of specific ion fragments. Plotting of m/e values characteristic for certain classes of compounds and/or individual components reveals the location of constituents in the gas chromatogram. This technique was applied to the identification of trimethylsilyl derivatives of unsubstituted and 2-hydroxy fatty acid methyl esters in mixtures obtained from acid catalyzed methanolysis of cat brain galactocerebrosides. The plot of total ionization intensity vs scan number generated the gas-liquid chromatogram. Mass chromatograms of m/e 73 and [M - 59]+ gave the locations in the gas-liquid chromatogram of the hydroxy fatty acid derivatives, and mass chromatograms of m/e 74 and [M]+ located the unsubstituted fatty acid derivatives. Integrated ion intensities were used to determine the composition of the mixture of fatty acids.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200010105
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    A model for ionization mechanisms in field desorption mass spectrometry (1976)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 3 (1976), S. 340-345 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The apparent discrepancy between theory and experimental practices in field desorption mass spectrometry has encouraged a study attempting to focus theoretical concepts more clearly into forms recognizable to the chemical investigator. Preliminary results indicate that best anode temperature for many compounds is independent of the applied voltage throughout the range available on the Varian MAT CH-5 double focusing mass spectrometer with the electron impact-field ionization-field desorption combined source. Studies of mass transfer indicate that desorption of the sample at the best anode temperature occurs in the absence of the applied field and at a rate which is indistinguishable from the rate of desorption in the presence of the field. These results and other observations, have led us to postulate a new mechanism of ion formation, involving chemical attachment reactions in a thin fluidized system. Clearly, the role of the field in this technique must be the subject of continued study.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200030613
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Urinary metabolites of L-threonine in type 1 diabetes determined by combined gas chromatography/chemical ionization mass spectrometry (1986)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 13 (1986), S. 535-540 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Metabolic profiling of urinary organic acids from patients with juvenile-onset (Type 1) diabetes mellitus have revealed significantly elevated levels of 2-hydroxybutyric acids. To test the hypothesis that these metabolites, as well as 4-deoxyerythronic acid, are derived from L-threonine, stable isotope-labeled threonine was infused into an insulin-deficient dog and the incorporation of 13C into these metabolites was monitored by gas chromatography/mass spectrometry. Electron ionization was relatively insensitive, but positive chemical ionization with ammonia as the reactant gas gave both protonated molecules and [M+NH4]+ ions, which could be analysed by selected ion monitoring. The isotope-labeled species of 2-hydroxybutyric, 4-deoxyerythronic and 4-deoxythreonic acids were observed, but 13C was not incorporated into other organic acids. Thus, it is proposed that L-threonine is a precursor of these metabolites.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200131004
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    Paper (German National Licenses)
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