Degree of solute inclusion in native beta-cyclodextrin: Chromatographic approach

The reversed-phase liquid chromatography retention and separation of a seri es of D,L dansyl amino acids were investigated over a wide range of salting -out agent (sucrose) concentrations using native beta-cyclodextrin as a chi ral stationary phase. An original treatment was developed to determine the number of sucrose molecules (n) excluded from the solute-beta-cyclodextrin cavity interface when the analyte transfer occurred. Using the n values, th e relative degrees of compound inclusion were calculated and correlated to the steric bulkiness of the solute. Thermodynamic parameter variations are discussed in relation to the inclusion degree of the dansyl amino acids. Th is numerical approach is a valuable tool to explore the steric effects impl ied in the host-guest complex formation.