HPLC retention and inclusion of imidazole derivatives using hydroxypropyl-beta-cyclodextrin as a mobile phase additive

Using the results of high performance liquid chromatography (HPLC), this pa per investigates the separation and inclusion of a series of weakly polar i midazole derivatives, with hydroxypropyl-beta-cyclodextrin (HP-beta-CD) in the mobile phase over a wide range of column temperatures. These compounds are used for the treatment of onychomycosis. Gibbs Helmholtz parameters (De lta(Delta H) and Delta(Delta S)) of two adjacent imidazole peak on a chroma togram were determined from the graph of the logarithm of the separation fa ctor, alpha, against the reciprocal of the temperature. A temperature depen dent reversal of the elution order between a pair of imidazole derivatives was studied. The results revealed that the main parameter determining interactions betwe en imidazole derivatives and HP-beta-CD increased as follows: HP-beta-CD do uble left right arrow solute hydrogen bonding interaction > HP-beta-CD doub le left right arrow solute complexation.