Solution studies of .beta.-cyclodextrin-pyrene complexes under reversed-phase liquid chromatographic conditions: effect of alcohols as mobile-phase comodifiers

Abstract

Studies of pyrene complexes with β-cyclodextrln, using reversed-phase (C18) liquid chromatography require a relatively more nonpolar mobile phase than water (mixtures of methanol-water >55% methanol) In order to achieve a reasonable retention time. Although methanol has a very low association constant with β-cyclodextrin, It becomes strongly competitive at high concentrations, resulting In very weak Interaction between pyrene and cyclodextrin. The presence of tert-butyl alcohol or cyclopentanol hi the medium Increases the strength of the β-cyclodextrin-pyrene complex by various orders of magnitude due to the formation of a ternary complex. In the presence of these alcohols as mobile-phase comodifiers, the Interaction between β-cyclodextrln and pyrene becomes evident at methanol concentrations In the range of practical use for HPLC. © 1991, American Chemical Society. All rights reserved.