Tuning of the selectivity in capillary electrophoresis by cyclodextrins illustrated by the separation of some structurally related phenothiazines.

Cyclodextrins were used to affect the selectivity of the capillary electrophoresis system in the separation of 10 widely used phenothiazines. It was shown that the addition of cyclodextrins substantially improved the selectivity. The effect of temperature and cyclodextrin concentration was studied on the resolution between the screened phenothiazines. The best results were obtained with 8 mM hydroxypropyl-beta-cyclodextrin at 15.5 degrees C. Under these conditions, a resolution of at least 1.5 between all phenothiazines could be obtained. In addition, the chiral separation of the enantiomers of trimeprazine could be accomplished. Structure separability relations between the phenothiazines showed that a change in the side chain at the R10 position had the greatest effect on the migration.