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  • 1995-1999  (1)
  • 1980-1984  (1)
  • 1940-1944
  • 1860-1869
  • Analytical Chemistry and Spectroscopy  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Negative-ion mass spectrometry in a commercial gas chromatography/ion-trap mass spectrometer system (1995)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 9 (1995), S. 1302-1309 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Commercial gas chromatography quadrupole ion-trap mass spectrometer (GC/ITMS) instruments have been used in a novel way for the study of negative ions formed from perfluorotributyl-amine and polychlorinated biphenyl compounds. Negative ions, formed during a normal electron impact ionization period in which 70 eV electrons were used, were isolated in an ion trap by the application of a negative DC voltage to the ring electrode that caused all positive ions to be ejected from the ion trap; in the subsequent analytical scan, negatives ions were detected with an electron multiplier biased normally so as to detect positive ions. The major negative-ion species detected from FC-43 were m/z 252 to m/z 633; 34 other negative-ion species were detected also, though in low abundance. The observed negative-ion mass range extended from m/z 252 to m/z 633. The signal-to-noise ratio of negative-ion mass spectra was enhanced by operation of the GC/MS instrument in GC mode and averaging the mass spectra acquired. In an examination of 3 hexachlorobiphenyl compounds, the molecular anion cluster around m/z 360 for the non-ortho-substituted congener 169 was observed with a signal-to-noise ratio of ca. 20 for 90 pg injected on column: the response for congener 169 was greater than that for congener 156 (mono-ortho-substituted) which, in turn, was greater than that for congener 153 (di-ortho-substituted).
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290091316
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  • 2
    Electronic Resource
    Electronic Resource
    Magnetic resonance study of diastereomeric interactions of nitroaromatic sulfxides with alcohols in solution (1984)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 22 (1984), S. 539-542 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of optically active (1R,2R)- and (1S,2R)-2-deuterio-2,3-dihydro-2-methyl-6-nitrobenzothiophene-1-oxide (3 and 4) is described. Several racemic aryl methyl carbinols in the presence of 3 or 4 give different chemical shifts for enantiomeric CH, CH3 and OH protons. These chemical shift differences are larger than those observed in analogous sulfoxide-alcohol pairs without nitro groups. Quinine and cinchonidine cause observable non-equivalence of methylene and aromatic protons in racemic 4. The magnitude of the diastereomeric shift difference is sensitive to temperature, solvent, concentration, nature of the π system and steric effects.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270220902
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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