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  • Physics  (2)
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  • 1
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The mass spectrometric fragmentation behaviour of four monosubstituted pyridazines (phenyl-3- and phenyl-4-pyridazinylmethanol, phenyl-3-pyridazinyl and phenyl-4-pyridazinyl ketone) was investigated. Fragmentation pathways were established by combined interpretation of the data obtained from high resolution measurements and from low-energy collision-activated dissociation mass spectra of the molecular ions as well as of several important fragment ions. A clear differentiation between these 3- and 4-substituted 1,2-diazines is possible for both sets of pyridazines. Only the spectra of the 3-isomers exhibit an abundant [M—H]+ peak, which indicates a cyclization of these ions involving one ring nitrogen atom. Another difference between the two isomeric phenylpyridazinylmethanols is the loss of OH from the molecular ion, as detected for the C-3 substituted compound only. For the phenylpyridazinyl ketones, the loss of CO from the molecular ion, which is only observed with the 3-isomer, permits an unequivocal differentiation.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 99-105 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: New methods are presented for the evaluation of ion structures and fragmentation pathways using tandem mass spectrometry (MS/MS) with low energy collision-induced dissociation. As an aid for mass spectroscopists, they incorporate a PC software package (named PDNL, written in Turbo-PASCAL 5.5 (Borland), running under DOS (Microsoft) with mouse-control). A database of almost 300 low energy MS/MS spetra is available for library searches. It utilizes a new, intensity-based matching algorithm fitting to the demand of MS/MS data. Computational methods have been developed for (i) the separation of the spectra of unresolved isobaric ions and evaluation of the ratio of the ion abundances, (ii) the evaluation of single-collision spectra using the multi-collisional data map, and (iii) the elucidation of collision-induced dissociation fragmentation pathways. Principal component analyses of sets of at least eight MS/MS spectra were used for a quick comparison of these spectra and for a summary of inter-ion relationships.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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