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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 11 (1988), S. 187-190 
    ISSN: 0935-6304
    Keywords: Multidimensional capillary GC ; GC-GC interface ; GC-tandem mass spectrometry ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The analysis of complex mixtures, such as essential oils requires high resolution chromatographic separation and even the use of very efficient columns cannot prevent the overlapping of certain peaks. This means that it is very difficult to obtain high quality mass spectra when the sample contains numerous constituants. The pre-separation by column or preparative GC leads to a considerable loss of material and, often, to the formation of artefacts. In order to overcome some of these difficulties, we have built a simple multi-column system that is connected to an MS-MS instrument. Two independent chromatographs equipped with capillary columns were connected. The interface, which consists of a modified PTV injector, gives the possibilities of direct transfer, back-flushing, heart-cutting, intermediate cold trapping, trace enrichment and selective sample introduction. These operations are controlled by a switching valve system (DANI-MFC 393 unit). The chromatographic system was first connected to a MS-MS instrument which may result in high MS and collision activated MS spectra.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 11 (1988), S. 881-890 
    ISSN: 0935-6304
    Keywords: Capillary gas chromatography ; Siloxane/silarylene copolymers as stationary phases ; OV-61-OH ; High temperature gas chromatography ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A commercially available silanol terminated silicone stationary phase, OV-61-OH (33% phenyl), and two phenyl-substituted siloxane/silarylene copolymers, Sila 3 (27% phenyl) and 4 (35% phenyl), have been evaluated for use as stationary phases in fused silica capillary columns for gas chromatography.Ulterations in column adsorptive activity, separation efficiency, stationary phase film thickness and selectivity after column conditioning for 50 h at 370°C have been studied. A high thermal stability was experienced with the stationary phases tested here. For OV-61-OH, the best thermal stability was obtained when coated on untreated fused silica, which illustrates the importance of grafting reactions here. The heat treatment resulted in some deactivation of adsorptive sites in the column. A higher degree of column deactivation was achieved when surface silylation was performed prior to coating. High thermal stability was achieved with Sila 3 when coated on such surfaces. Sila 3 would thus be preferred in cases when high thermal stability in combination with high dsorptive inertness is desired.Sila 4 showed low column bleeding at 370 °C, but prolonged heating at this temperature resulted in the broadening of n-alkane peaks when eluted at 90 °C. This indicates that excessive crosslinking has taken place during the heat treatment and the minimum allowable column operation temperature is thereby increased to ca. 120 °C. The separation of aza-arenes and of triglycerides are shown as applications.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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