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  • 1
    ISSN: 1040-7685
    Keywords: high temperature liquid chromatography ; nonaqueous mobile phases ; temperature programming ; packed capillary columns ; ceramic frit ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The need for a high resolution chromatographic technique for analyzing compounds that are heavy, relatively polar, have low water solubility, and are not adequately separated by regular HPLC methods, has led to the development of a high temperature liquid chromatography system. The increased diffusion coefficients and reduced viscosity at higher temperatures resulted in high separation velocities and allowed long columns to be used. The HTLC system contained 70 cm columns and nonaqueous mobile phases. Packed capillary columns prevented radial temperature gradients which otherwise would reduce the efficiency. The capillary columns were packed with a reversed phase material (ODS) using supercritical carbon dioxide as the slurry fluid. A new method for preparing a ceramic frit inside the column was developed. The frit withstood pressures of at least 600 bar. The robustness of the columns in a nonaqueous environment with elevated temperature was tested and found satisfactory for 150 injections with a temperature program at each injection. Isothermal elution or temperature programming in the 50-150°C range reduced the analysis time significantly. Compounds which were completely retained at room temperature eluted with good peak shape at elevated temperature.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 22 (1999), S. 283-286 
    ISSN: 0935-6304
    Keywords: Evaporative light scattering detection ; capillary nebulizer ; packed capillary ; columns ; high temperature liquid chromatography ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---No abstract
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0935-6304
    Keywords: Large volume injection ; packed capillary LC ; temperature programming ; retinyl esters ; vitamin A ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---A non-aqueous isocratic reversed-phase packed capillary high performance liquid chromatography method for the determination of retinyl esters, utilizing temperature programming and on-column focusing large volume injection, has been developed. The stationary phase material was C30, and the mobile phase consisted of acetonitrile-dichloromethane (70 : 30, v/v). A three-step temperature program, starting at 10°C for 10 min, then 1°/min to 30°C, and finally 2.5°/min to 70°C, was found most appropriate. Compared to an isothermal separation at 25°C, this temperature program provided improved peak resolution, enhanced peak shapes of the last eluting compounds, and a reduction of the overall elution time. A mass limit of detection of 27 pg was found with respect to retinyl palmitate, using UV detection with an “U” shaped flow cell at 327 nm. This corresponds to a concentration limit of detection of 2.7 pg/μL, when utilizing an injection volume of 10 μL. The concentration of retinyl palmitate in arctic seal liver samples was estimated to be 62.6 μg/g liver.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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