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  • 1
    ISSN: 1040-7685
    Keywords: supercritical fluid chromatography ; stationary phases ; packing materials ; packed capillary columns ; cyanobiphenyl-substituted polymethylhydrosiloxane ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Nine isomeric cyanobiphenyl-substituted (25%) polymethylsiloxane (CBP) stationary phases were coated and immobilized by free-radical crosslinking on silica packing materials for use in supercritical fluid chromatography (SFC). The selectivities of these packing materials to benzene derivatives, polycyclic aromatic hydrocarbons (PAHs), and double bonds in fatty acid methylesters (FAMEs) were determined. Among the nine isomeric CBP-coated packing materials, the o, p-CBP phase was found to be the most selective to both double bonds and aromatic isomers under SFC conditions. The durability of the packing materials was evaluated by measuring the changes in selectivity with SFC use. The loss in selectivity was less than 0.20% after being continuously washed by supercritical carbon dioxide at 100°C and 300 atm for more than 100 h.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Microcolumn Separations 4 (1992), S. 521-527 
    ISSN: 1040-7685
    Keywords: cyanobiphenyl polysiloxanes ; gas chromatography ; stationary phases ; synthesis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Nine isomeric cyanobiphenyl-substituted polysiloxanes were synthesized using a four-step procedure and tested as stationary phases in open tubular column gas chromatography.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1040-7685
    Keywords: stationary phases ; cyanobiphenylpolysiloxanes ; gas chromatography ; supercritical fluid chromatography ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Nine different 25% cyanobiphenyl-substituted polysiloxane (CBP) stationary phases were evaluated for use in gas and supercritical fluid chromatography. They were easily coated and cross-linked on fused silica capillaries to produce highly efficient columns. For a 200 μm i.d. column, an efficiency of as high as 5,100 plates m-1 was obtained. For most of the new phases, the upper temperature limit was 300°C. A comparative study of the chromatographic behaviors of the cyanobiphenyl and commercial reference phases was made. Some of the cyanobiphenyl stationary phases showed polarities higher than those for carbowax 20M or 50% cyanopropyl. All six positional isomers of dodecylxylene and the five isomers of four-ring polycyclic aromatic hydrocarbons were baseline resolved on GC capillary columns with certain of the cyanobiphenyl phases, demonstrating higher selectivity over SE-54 or Carbowax 20M phases. In SFC, a cyanobiphenyl column provided better separation of a standard coal tar sample than columns with biphenyl or cyanopropyl phases. The retention behavior of fatty acid methyl esters and a mixture of polar solutes was investigated on the cyanobiphenyl and references phases. With respect to certain solute pairs, the selectivities of the new stationary phases were found to increase with temperature. The new cyanobiphenyl phases were found to be useful for GC and SFC separations of various classes of complex mixtures including essential oils, explosives, and polycyclic aromatic hydrocarbons.
    Additional Material: 8 Ill.
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