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  • Calculation of concentration of organic modifier  (2)
  • Hydrophobicity  (2)
  • Rekker's hydrophobic fragmental constant  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 17 (1983), S. 633-639 
    ISSN: 1612-1112
    Keywords: Macro porous polystyrene gel and the ion-exchange resins ; Aromatic acids ; Hydrophobicity ; Dissociation constant ; lon-pair
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The retention behaviour of aromatic acids was examined in a reversed-phase mode liquid chromatography. Macro porous styrene-divinylbenzene copolymers were selected on the basis of their chemical stability throughout the entire pH range. The effect of addition of a hydrophobic ion in the eluent and that of an ion-exchange group on the packing were discussed in relation with the hydrophobicity and the dissociation constant of solutes. The maximum capacity ratios of the acids on apolystyrene gel are linearly related with the hydrophobicity. The prediction of the retention time of aromatic acids could be possible by combination of their hydrophobicity and their dissociation constants.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 12 (1979), S. 77-82 
    ISSN: 1612-1112
    Keywords: Liquid chromatography ; Qualitative analysis ; Hydrophobicity ; Reversed phase mode chromatography ; Calculation of solvent concentration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The possibility of qualitative analysis by liquid chromatography is discussed in systems of polystyrene gel or chemically bonded octadecyl packing with alcohols as standard compounds. Rekker's hydrophobic fragmental constants are used for identification purposes. Capacity ratios for alcohols can be calculated from the hydrophobicities in spite of changes in solvent mixture ratios if the capacity ratio for an internal standard compound is measured.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 4 (1981), S. 454-460 
    ISSN: 0935-6304
    Keywords: Reversed-phase mode liquid chromatography ; Rekker's hydrophobic fragmental constant ; Calculation of concentration of organic modifier ; Prediction of retention time ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The utility of Rekker's hydrophobic fragmental constant has been examined for optimization of reversed-phase mode liquid chromatographic separations. The chromatographic behavior of about 60 non-ionic compounds was measured in different acetonitrile/water mixtures and the logarithm of their capacity factors (log k) was correlated with their calculated hydrophobicities (log P). Linear relations were found in each case between log k and log P. The slope of the various lines was related to the percentage concentration of acetonitrile in the mobile phase. It was shown that, by using nine stand ard compounds and measuring their capacity factors in five eluents with different acetonitrile concentrations, the retention time could be predicted for 60 compounds. Calculation of the concentration of the organic modifier was also possible in a system of well coated octadecyl bonded packings with acetonitrile/water mixtures as eluent. Prediction of the capacity factor was accomplished to within 5% error.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 6 (1983), S. 20-26 
    ISSN: 0935-6304
    Keywords: Reversed-phase mode liquid chromatography ; Rekker's hydrophobic fragmental constant ; Calculation of concentration of organic modifier ; Prediction of retention time of phenols ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The chromatographic behavior of phenols in reversed-phase mode liquid chromatography differs from that of non-ionic compounds such as alkyl alcohols, alkylbenzenes, halogenated benzenes, polyaromatic hydrocarbons, and aromatic acids. Therefore, the retention times of 61 phenols were measured in a system of an octadecyl bonded silica gel and acetonitrile/water mixtures. The logarithm of the capacity ratio (log k') was found to be a linear function of the hydrophobicity (log P) in acidic acetonitrile/water mixtures. This result was applied to a different octadecyl bonded silica gel. Eight phenols were selected as standard compounds, and their log k' values were measured in 0.05 M phosphoric acid in 10 to 90% acetonitrile/water mixtures. An empirical polynomial relation was obtained between the concentration of acetonitrile and the slope of the log k' vs log P curve. Finally the capacity ratio of all phenols were calculated in given eluents by the equations derived from the measurements of standard compounds and the calculated log P values. The difference between predicted capacity ratios and measured ones was within 10%.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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