Enantiomeric separation of basic compounds using heptakis(2,3‐di‐ O ‐methyl‐6‐ O ‐sulfo)‐β‐cyclodextrin in combination with potassium camphorsulfonate in nonaqueous capillary electrophoresis: Optimization by means of an experimental design

The enantiomeric separation of a series of basic pharmaceuticals (β‐blockers, local anesthetics, sympathomimetics) has been investigated in nonaqueous capillary electrophoresis (NACE) systems using heptakis(2,3‐di‐ O ‐methyl‐6‐ O ‐sulfo)‐β‐cyclodextrin (HDMS‐β‐CD) in combination with potassium camphorsulfonate (camphorSO 3 − ). For this purpose, a face‐centered central composite design with 11 experimental points was applied. The effect of the concentrations of HDMS‐β‐CD and camphorSO 3 − on enantioresolution was statistically evaluated and depended largely on the considered analyte. The presence of camphorSO 3 − was found to be particularly useful for the enantioseparation of compounds with high affinity for the anionic CD. CamphorSO 3 − seems to act as a competitor, reducing the affinity for the CD, probably by ion‐pair formation with these analytes. For compounds with lower affinity for HDMS‐β‐CD, the combination of camphorSO 3 − and the CD appeared to have a favorable effect on enantioresolution only if the optimal CD concentration could be reached. On the other hand, for compounds characterized by a very low affinity for the anionic CD, the association of camphorSO 3 − and HDMS‐β‐CD is always unfavorable. Finally, experimental conditions were selected by means of the multivariate approach in order to obtain the highest resolution ( R s ) value for each studied compound.