Relationships of Enantioselective Retention of Chiral Oxazolopyrroloquinolones on a Stationary Phase with Grafted Ristocetin A Antibiotic from Aqueous Methanol Solutions

The mechanisms of retention and separation of the enantiomers of chiral oxazolopyrroloquinolones on a stationary phase with grafted macrocyclic antibiotic ristocetin A under conditions of high-performance liquid chromatography with aqueous methanol mobile phases have been studied. The retention factor was found to decrease monotonically when the CH3OH concentration in the mobile phase increased to 90 vol %; then it slightly increased as the composition of the mobile phase approached pure methanol. The thermodynamics of adsorption of oxazolopyrroloquinolones in different regions of this dependence was studied. A mathematical model has been proposed; it describes well the experimental data and allows for analyte solvation in the mobile phase and competitive adsorption (with mobile phase components) on a chiral selector. The results were compared with previously obtained data for water-acetonitrile mobile phases. The reasons for the observed differences were discussed.