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  • 1
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Reversed stationary phases ; Hydrophobic parameter ; Water/methanol eluent mixtures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The hydrophobic retention characteristics of stationary ligands for reversed-phase high-performance liquid chromatography have been evaluated from the slope (r-value) of the plots relating the capacity factors (log k′) of selected aliphatic and aromatic compounds with the reciprocal of methanol concentration (log (1/[MeOH])) in aqueous mobile phase. Octadecylsilyl (ODS), trimethylsilyl (TMS) and phenyldimethylsilyl (phenyl) groups were selected as the stationary ligands bonded to silica support. On ODS or TMS silicas, unlike on phenyl silica, aliphatic compounds gave slightly larger r-values than aromatic compounds, indicating that the shape of the ligand recognizes the hydrophobic surfaces of aliphatic and aromatic solute molecules. On TMS and phenyl silicas, the degree of solute hydrophobicity contributing to its retention is about 90% and 85% of that on ODS silica, respectively. On the other hand, on TMS and phenyl silicas, the polar functional group on the solute molecule brought about a smaller decrease in retention than on ODS silica.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Linear solvation energy relationship (LSER) ; Hydrophobic adsorption ; Octanol/water partition coefficient ; Solute-solvent interaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The effects of the polar functional group of a solute on the r-value (the slope of the log-log plots of capacity factor vs. reciprocal of the organic solvent concentration in an aqueous binary mobile phase) and on the 1-octanol/water partition coefficient are compared, based on the linear solution energy relationship concept. Though both effects are closely related to the solute-solvent interaction, the effect on the partition coefficient depends on the difference in the abilities of the organic solvent and water to interact with the solute, while the effect on the r-value depends on the ability of the solute to interact with the solvent (especially water). The mobile phase composition, as far as it is in the intermediate range, causes little change in the effect of the polar functional group on the hydrophobic retention of the solute. Consequently, the r-value was confirmed to represent the hydrophobic interaction between the solute and ligand.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Hydrophobic parameter ; Capacity factor variation ; Organic modifier concentration ; Displacement model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The dependence of the capacity factor (k′) on the concentration of the organic modifier (D) in the aqueous binary mobile phase in reversed-phase high-performance liquid chromatography has been investigated to evaluate the hydrophobicity of the solute molecule. The r-values, defined as the slope of log k′ vs. log(1/D) plots, were measured for various solutes and related to the non-polar surface area and the partition coefficients. The r-value was found to be a good indication of solute hydrophobicity. Detailed investigation of the results allowed to consider statistically the molecular posture of the solute adsorbed onto the stationary alkyl ligand.
    Type of Medium: Electronic Resource
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