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  • 1
    Electronic Resource
    Electronic Resource
    Plasma quantitation of warfarin and warfarin alcohol by gas chromatography chemical ionization mass spectrometry in patients on warfarin maintenance therapy (1979)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 6 (1979), S. 208-211 
    Details
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A quantitative method has been developed to measure plasma concentrations of warfarin and warfarin alcohol. The analytical procedure uses deuterated analogues as internal standards, and the technique of selected ion monitoring following gas chromatography methane chemical ionization mass spectrometry of the 4′-methyl ethers of warfarin and warfarin alcohol. Concentrations of warfarin and warfarin alcohol have been measured in plasma samples from 43 patients maintained on chronic warfarin therapy and compared with the ‘apparent warfarin’ concentration as measured by a fluorometric procedure. The study demonstrated a high degree of correlation between the gas chromatographic mass spectrometric derived sum of the individual concentrations of warfarin and warfarin alcohol, and the ‘apparent warfarin’ concentration determined from a spectrofluorometric assay.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200060508
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  • 2
    Electronic Resource
    Electronic Resource
    A chemical ionization gas chromatographic mass spectrometric assay for octopamine and tyramine in rat brain (1981)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 8 (1981), S. 170-173 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A method has been developed for the quantitation of the putative phenolamine neurotransmitter octopamine, and its precursor tyramine, in brain tissue. The procedure employs methane chemical ionization of the pentafluoropropionate derivatives of octopamine and tyramine together with the use of deuterated internal standards and selected ion monitoring. Deuterated analogues of octopamine and tyramine are added to brain homogenates in aqueous perchloric acid and ion exchange is used to isolate the brain amines. The method is capable of measuring 20 pg of octopamine and tyramine. The measured concentration (ng g-1 wet tissue) of octopamine and tyramine in rat brain was as follows: whole brain (less cerebellum) (0.6 and 2.2); hypothalamus (3.2 and tyramine value not statistically significant); striatum (0.5 and 11.8) and cortex (0.6 and 1.0). Administration of pargyline resulted in an increase (around ten-fold) in octopamine and tyramine concentration in all the above brain regions. In contrast α-methyltyrosine produced only a small increase (50%) in the concentration of tyramine in the striatum.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200080408
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  • 3
    Electronic Resource
    Electronic Resource
    Identification by methane chemical ionization gas chromatography/mass spectrometry of the products obtained by steam distillation and aqueous acid extraction of commercial Piper methysticum (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 17 (1988), S. 371-376 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Bornyl cinnamate has been identified as a constituent of kava resin and of the steam distillate of Piper methysticum. 5-Hydroxydihydrokawain was identified in commercial samples of P. methysticum originating from Vanuatu provided an initial aqueous extraction was employed. Commercial preparations, and fresh samples of the root of this plant from Fiji, lacked this compound. Two previously described N-cinnamoyl pyrrolidine alkaloids were also observed along with stigmasterol in kava resin from Fiji and Vanuatu. The products derived from aqueous 2 M hydrochloric acid extraction of P. methysticum were determined from methane chemical ionization gas chromatography/mass spectrometry analysis which identified a series of hydroxylated compounds (15a-d) derived from formal decarbonylation of the parent kava lactones. The products (13a-c) of dehydration of these compounds were also observed. The efficiency of kava resin extraction from plant material by water (the traditional method of preparation of the kava beverage) was typically 5-10% of that recovered by direct extraction with an organic solvent.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200170505
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  • 4
    Electronic Resource
    Electronic Resource
    Methane negative ion chemical ionization fragmentation processes of deuterated analogues of Ortho-, meta- and para-tyramine-N,O-dipentafluoropropionate derivatives (1986)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 13 (1986), S. 299-304 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The methane negative ion chemical ionization (NICI) mass spectra of the three isomeric tyramine-N-O-dipentafluoropropionate derivatives are unique insofar as each has a different base peak in contrast to their methane positive ion chemical ionization (PICI) mass spectra which are very similar in appearance. Deuterium-labelling studies in the three isomeric tyramine derivatives have elucidated the fragmentation processes accompanying the electron capture NICI process for each derivatized compound.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200130607
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