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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 17 (1994), S. 308-311 
    ISSN: 0935-6304
    Keywords: Capillary GC ; Mass selective detection ; Multidimensional GC-MSD ; Fish oil ; Furan fatty acids ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The separation and analysis of furan fatty acids and other minor component fatty acids present at very low concentrations in complex sample matrices, such as fish oil or lipids derived from liver and testes, require several pre-analytical separation steps if single column gas chromatography is to furnish sufficient resolution: after extraction and transesterification hydrogenation, urea complex precipitation and argentation TLC have been applied prior to GC analysis of furan fatty acids.By using multidimensional GC-MSD with cooled injection and flow-controlled column switching with intermediate cold trapping, it has been possible to identify directly the methyl esters of furan fatty acids without further pre-analytical separation.The most common of the furan fatty acids can be subdivided into two groups depending on whether they bear a propyl or pentyl side group in the 5-position of the furan ring. In addition to the eight furan fatty acids known to be present in fish oil, six new ones were identified, four with propyl substitution and two with pentyl substitution. Four have earlier been reported to be present in the hepatopancreas of crayfish and in fish tissue, whereas the propyl-substituted 16,19-epoxy-17,18-dimethyldocosa-16,18-dienoic acid and the pentyl-substituted furan fatty acid 6,9-epoxy-7-methyltetradeca-6,8-dienoic acid were hitherto unknown.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 22 (1991), S. 497-503 
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In principle, Raman measurements provide information about vibrational frequencies and intensities. Working with polarized light provides additional information about the Raman scattering tensor components. The special conditions relating to the near-infrared-Fourier transform (NIR-FT) Raman technique may preclude adaptation of some of the techniques employed for measurements with linear polarized light in ‘classical’ Raman spectroscopy in the visible range. The experimental conditions for measurements of depolarization ratios of liquids (benzene, mesitylene, p-xylene and carbon tetrachloride) using different experimental geometries with an NIR-FT-Raman spectrometer were elucidated. The FT technique allows the rapid and simple determination of depolarization ratios with a quality sufficient to assign the bands to totally or non-totally symmetric species. The possibility of determining the orientation of molecules in non-crystalline solids is also demonstrated. Finally, the feasibility of measuring the different components of the Raman scattering tensor of a single crystal of sodium chlorate is considered.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Using NIR-FT Raman spectroscopy we have obtained useful spectra of many kinds of biomaterials. These spectra contain - with only simple sample preparation - information that can be used both for component analysis and for tissue identification. In addition, pathological changes in the spectra of eye lenses and of brain, liver and colon tissues are observed, demonstrating the usefulness of the technique as a tool of medical diagnosis.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Surface-enhanced Raman (SER) spectra of the xanthine dyes rhodamine 6G (R6G) and oxazine 1 (OX1) were measured with near-infrared excitation employing Fourier transform Raman spectroscopy. Both dyes exhibit strong SER signals on Ag and Au surfaces. The enhancement factors were evaluated based on the determination of the number of adsorbed molecules. In the absence of additional electrolyte, the enhancement factors for R6G on Ag and Au sols are 1.3 × 104 and 1.6 × 104, respectively. This enhancement is operative for all adsorption sites and is ascribed to the classical electromagnetic mechanism. On activation of the Ag sol by chloride ions, the enhancement factors for R6G and OX1 are 4.3 × 107 and 7.6 × 105, respectively. This increased enhancement which occurs at a small number of specific adsorption sites is ascribed to the charge-transfer mechanism. For R6G this enhancement mechanism is stronger by a factor of 47 than for visible excitation. The electrolyte-induced activation is not possible for Au sols or precipitates of Ag or Au on filter-papers. These metal-coated filter-papers may provide appropriate SER-active surfaces for analytical applications of the SER effect in combination with Fourier transform Raman spectoscopy.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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