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  • 1
    Digitale Medien
    Digitale Medien
    The preparation of non-extractable methylphenylpolysiloxane stationary phases for capillary column gas chromatography (1982)
    Springer
    Chromatographia 15 (1982), S. 335-340 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Capillary gas chromatography ; Fused silica capillary columns ; Crosslinked phenyl polysiloxanes ; Non-extractable stationary phases
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The synthesis of methylphenylpolysiloxane polymers and their use in the preparation of crosslinked, non-extractable stationary phases for fused-silica capillary columns are described. By preparing more viscous phenyl-containing polymers than are commercially available, stationary phase films of these polymers could be efficiently coated on fused-silica capillary columns and stabilized by a free radical crosslinking mechanism using peroxides. Four methylphenylpolysiloxane polymers containing different phenyl concentrations were prepared. These included three polymers containing 50% phenyl and one polymer containing 70% phenyl. Two of the 50% phenyl polymers had one phenyl and one methyl group attached to each silicon atom. One of these also had 1% vinyl incorporated. The third 50% phenyl polymer was synthesized in such a way that one half of the silicon atoms had two phenyl groups attached while the rest contained dimethyl groups. The 70% phenyl polymer also had 4% vinyl incorporated. Due to the intrinsic thermal stability of these phenyl phases and the enhanced film stability achieved by crosslinking, the 70% phenyl phase could be utilized up to 400 °C. Using the methods described in this paper, highly efficient and thermally stable fused silica capillary columns coated with crosslinked methylphenylpolysiloxane stationary phases can be successfully prepared.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02259213
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  • 2
    Digitale Medien
    Digitale Medien
    Characterization of glass, quartz, and fused silica capillary column surfaces from contact-angle measurements (1981)
    Springer
    Chromatographia 14 (1981), S. 387-397 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Capillary columns ; Fused silica ; Contact angle ; Wettability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary This paper describes the systematic characterization of glass and the newly introduced fused silica and quartz capillary columns from surface wettability measurements. Common gas chromatographic stationary phases were used in capillary-rise measurements at temperatures up to 300°C. By construction of Zisman plots and using the Cassie equation, the relative surface concentrations of wettable and non-wettable groups were determined. By application of the Fowkes equation, the dispersion force component of the surface energy was investigated. The influence of various surface treatments such as leaching, silylation, and polymeric film formation are discussed. Wettability measurements were also used to evaluate the thermostability of various treated surfaces and to compare the surface properties of glass, quartz, and fused silica. The wettability of the surfaces with selected stationary phases as a function of temperature is also discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02262872
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  • 3
    Digitale Medien
    Digitale Medien
    Determination of surface hydroxyl concentration on glass and fused silica capillary columns (1982)
    Springer
    Chromatographia 15 (1982), S. 584-586 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Surface hydroxyl quantification ; Siliceous capillary columns ; Capillary gas chromatography
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The concentration of surface hydroxyl groups on three types of capillary columns was determined by exchanging the hydroxyl protons with tritium. The tritium was quantified by combustion to tritiated water followed by scintillation counting. The number of hydroxyl groups on a leached and presumably hydroxylated Pyrex glass capillary column was found to be about 2.8 groups per square nanometer. This value was slightly less than the 4.6 groups per square nanometer that is generally accepted for a fully hydroxylated porous silica. Dehydroxylation of the same glass by heating at 600°C left only 0.4 groups per square nanometer while an untreated fused silica had only 0.2 groups per square nanometer.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02280379
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  • 4
    Digitale Medien
    Digitale Medien
    Application of capillary supercritical fluid chromatography to the analysis of a middle distillate fuel (1984)
    Springer
    Chromatographia 18 (1984), S. 542-545 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Supercritical fluid chromatography ; Alumina ; Fused silica capillary columns ; Middle distillate fuel
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The application of capillary supercritical fluid chromatography (SFC) to the analysis of a middle distillate fuel is described. Small diameter (50μm i.d.) fused-silica capillary columns coated with crosslinked 50% phenyl polymethylphenyl siloxane provided high separation efficiency and good compatibility with flame ionization detection. High resolution separations of the chemical class fractions obtained by adsorption chromatography on alumina were obtained using carbon dioxide as the supercritical mobile phase and simple pressure programming techniques. In addition to the less polar fuel components, supercritical carbon dioxide allowed chromatography of the nitrogen-containing polycyclic aromatic hydrocarbon fraction and the hydroxylated polycyclic aromatic materials.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02265691
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  • 5
    Digitale Medien
    Digitale Medien
    Effect of viscosity on stationary phase stability in capillary column gas chromatography (1982)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 5 (1982), S. 413-416 
    Details
    ISSN: 0935-6304
    Schlagwort(e): Capillary gas chromatography ; Stationary phase stability ; Stationary phase viscosity ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: With recent advances in column technology it is now possible to prepare highly efficient, very inert, and thermally stable capillary columns coated with nonpolar polysiloxane stationary phases. Unfortunately, the same degree of success has not been achieved for some of the more polar polysiloxane phases. A parameter that has been studied little in the past in relation to stationary phase film stability is the viscosity of the stationary phase. In this paper the efficiency and stability of coated columns are correlated to the viscosity of the phase. Due to their structure, the viscosity of the phenyl-containing polysiloxanes change rapidly with temperature and hence, thin-film coatings are not stable at elevated temperatures. By using high viscosity phenyl-containing methylphenylpolysiloxanes which were recently synthesized, efficient and stable columns have been prepared.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jhrc.1240050804
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