The use of mobile phase pH and column temperature to reverse the retention order of enantiomers on chiral-AGP®

Summary Enantiomeric separation of mosapride and a structurally related compound was performed using chiral chromatography and experimental design. Unique effects of mobile phase pH and column temperature made it possible to control the elution order of the enantiomers when using Chiral-AGP as the solid phase. At a low mobile phase pH (<6) the (R)-enantiomer of mosapride elutes before the (S)-form whereas the (S)-enantiomer elutes first at a high mobile phase pH (>6). By using a mobile phase pH around 6, the column temperature could also be used to control the elution order of the enantiomers of mosapride. Similar effects of mobile phase pH and column temperature were obtained for the enantiomers of a structurally related compound, a metabolite (M1). Isocratic chromatographic systems made it possible to determine enantiomeric impurities less than 0.1% in the respective enantiomer of mosapride. The enantiomers of mosapride as well as the enantiomers of M1 could easily be separated simultaneously using Chiral-AGP and a simple gradient elution. Part of this work has been presented as lectures at HPLC'96 in San Francisco USA, at AAPS-96 in Seattle USA and as a poster at HPLC'95 in Innsbruck Austria.