[Enantioseparation of quinazolone derivatives using an AGP-based liquid chromatography stationary phase]

An AGP-based chiral stationary phase has been applied successfully for enantioseparation of 4(3H)-quinazolone derivatives. Chiral-AGP is proved to be an excellent selector, as optimized chromatographic conditions allow with one exception baseline resolution for the enantiomers of the potential cholecystokinin antagonist compounds (alpha = 1.19-1.85). Retention and enantioselectivity could be modified to a large extent by varying the eluent pH and adding organic solvents with different types i.e. acetonitrile and 2-propanol to the buffered mobile phase. It was established that by increasing the eluent pH from 6.0 to 7.0 the retention factors of of the model compounds bearing no protonable groups are increased in the presence of 7 v/v % (1.33 M) acetonitrile. However further increasing the acetonitrile content up to 10 v/v % or addition of 2-propanol in equimolar concentration (1.33 M) no similar changes could be detected with the same modification in the eluent pH. These observations are explained by changes in the sorption properties of the selector determined simultaneously by the type and concentration of organic modifier and also the eluent pH. The experimental data give further insight into the chromatographic mechanism on a Chiral-AGP column.