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  • 1
    ISSN: 1572-8854
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Crystals of the title compound, C12H18O8, are orthorhombic:P212121,a = 7·260(5),b = 9·483(6),c = 20·199(6) Å,Z = 4. The structure has been solved from the Patterson synthesis, and refined to anR-factor of 8·4% by full-matrix least-squares methods. The 6-membered rings are each in thechair conformation and arecis-fused at the 4a, 8a ring-junction. The structure led to an explanation of an unusually large chemical shift in the nmr signal from one of the methylenic hydrogen atoms on C(7).
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 11 (1984), S. 284-289 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A capillary gas chromatography column directly interfaced to a mass spectrometer was used for the analysis of sixteen benzodiazepines. The thermal stability of the drugs was found to be related to their chemical structure. Nine of the benzodiazepines were thermally unstable indicating that care should be taken in the interpretation of gas chromatographic data from this class of drugs. The unstable benzodiazepines were: ketazolam which decomposes to diazepam; N-4 oxides (chlordiazepoxide and demoxepam) which lose an oxygen radical; aromatic 7-nitro compounds (nitrazepam and clonazepam) which are partially reduced to the corresponding amine; α-hydroxy ketones (lorazepam and oxazepam) which decompose with the loss of water and N-methyl-α hydroxy ketones (Iormetazepam and temazepam) which partially decompose with the loss of a hydrogen molecule to produce the corresponding α,β-diketones. Few problems were encountered in distinguishing the drugs by their mass spectra, the exceptions being ketazolam which decomposes to diazepam and demoxepam which decomposes to desmethy Idiazepam. In general, good spectra were obtained from 20-50 ng of drug injected. However, for those compounds where the decompositions were not quantitative (nitrazepam, clonazepam, Iormetazepam, temazepam) detection limits were poor.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 12 (1985), S. 588-592 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A thermospray liquid chromatograph/mass spectrometer interface has been applied to the analysis of non-polar materials. The interface, which is designed to permit the continuous introduction of liquid into a mass spectrometer, incorporates a new ionization technique, which has proved capable of ionizing polar compounds and species which are ionic in solution. This new ionization method has been successfully applied to the analysis of a complex mixture of phenanthrenic materials. The results have been compared with data obtained by electron impact LC/MS and demonstrate the utility of thermospray ionization in the liquid chromatographic/mass spectrometric screening for compounds in this class, and suggest that the technique may be applied to a wide variety of non-polar compounds.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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