About the role of enantioselective selector-selectand interactions and the mobilities of diastereomeric associates in enantiomer separations using CE

It is generally accepted that the selective binding of enantiomers of the chiral analyte to a chiral selector is necessary for enantioseparations in CE, whereas the role of mobility differences between the temporary diastereomeric associates formed between the enantiomers and the chiral selector has been commonly neglected. One of the authors of this study suggested in 1997 that the mobility difference between the diastereomeric associates of two enantiomers with the chiral selector may be solely responsible for a separation of enantiomers in CE and enantioselective selector-selectand binding may be not necessarily required. Several indirect confirmations of this hypothesis have been described in the literature within the last few years but a dedicated study proving this concept has not been published yet. The present data obtained for the two chiral antimycotic drugs ketoconazole and terconazole by CE and NMR spectroscopy unequivocally support this concept.