RETENTION BEHAVIOR OF BETA-CYCLODEXTRIN COMPLEXES OF ANTHRACENE AND PYRENE USING REVERSED-PHASE LIQUID-CHROMATOGRAPHY - THE EFFECTS OF TERT-BUTANOL AND CYCLOPENTANOL

The effects of tert.-butanol and cyclopentanol on the formation of beta-cyclodextrin (beta-CD)-anthracene and beta-CD-pyrene complexes have been studied using reversed-phase liquid chromatography. The retention times of anthracene and pyrene were monitored when eluted in a C18 column with mobile phase mixtures consisting of methanol, water, beta-CD, and a small amount of tert.-butanol or cyclopentanol. Plots of capacity factor of anthracene versus concentration of beta-CD in the mobile phase in methanol-water mixtures and in mixtures containing 1% (v/v) cyclopentanol or tert.-butanol as secondary modifiers showed very similar trends. This suggests that anthracene forms weak complexes with beta-CD, and that the presence of these secondary mobile phase modifiers have little effect on the beta-CD-anthracene inclusion reaction. In contrast, pyrene showed no discernable change in retention time with increases in beta-CD concentration. However, in the presence of 1% (v/v) tert.-butanol or cyclopentanol, capacity factor of pyrene decreased drastically, more in 1% (v/v) cyclopentanol than in 1% (v/v) tert.-butanol. Formation of a ternary beta-CD-pyrene-alcohol complex has been proposed to explain the effects.