INCLUSION REACTION OF SOME FLUOROPHORES WITH BETA-CYCLODEXTRIN AND ITS EFFECT ON THEIR REVERSED-PHASE HPLC RETENTION

The thermodynamics of the inclusion reaction of flavonol, 7-methoxyfla vonol and 3-phenyl-7-hydroxycoumarin (L) with beta-cyclodextrin (CD) h as been studied fluorometrically with special reference to the effect of organic solvents (S). The equilibrium constants for this reaction w ere determined in aqueous methanol, ethanol, acetonitrile, acetone, di methyl sulfoxide, and N,N-dimethylformamide. The dependence of the con stants on the content of the respective S was attributable to the subs titution of S included in CD with L as CD.nS+L reversible arrow CD.L+n S. Also, the inclusion constants of S with CD, beta(n)=[CD.nS][CD](-1) [S](-n), were found to be linearly correlated with the solubility para meterof S for both n=1 and 2. When aqueous methanol was employed as a mobile phase, the retention behavior of coumarins on a reversed-phase HPLC column was studied in the presence of beta-CD as a mobile-phase c omponent. The change in the capacity factors could be reasonably expla ined by the same inclusion scheme as that mentioned above.