Application of modified cyclodextrins in capillary electrophoresis for enantiomeric resolution of propranolol and analogues

The enantio-resolution of propranolol and four derivatives was examined by free solution capillary electrophoresis (FSCE) using various cyclodextrin molecules. Of the three modified cyclodextrins investigated, hydroxyethyl-β-cyclodextrin provided the largest chiral resolution values for all five analytes. This may be linked to its extended hydrogen bonding chains on the cyclodextrin rim. Methyl-β-cyclodextrin and heptakis (2,3-di-O-acetyl) β-cyclodextrin gave lower maximum analyte resolutions, probably due to differences in their macrocyclic structure and hydrogen bonding ability. The presence of a bulky, non-polar alkyl grouo on the analytes was found to enhance chiral recognition. Methanol was found to have a varied effect on chiral resolutions, dependent on the type of cyclodextrin and structure of the analyte.