Enantiomeric separation by capillary electrophoresis with an electroosmotic flow-controlled capillary

Perfect control of electroosmotic flow (EOF) was achieved by dovetailing successive multiple ionic–polymer layer (SMIL) coated capillaries. The direction and magnitude of the EOF was perfectly controllable over the pH range 2–13. Zone diffusion was not observed, even if the inner wall of the dovetailed capillary was discontinuous, or if the sample zone passed through the connected part of the capillary because the RSDs of migration time, theoretical plates, symmetry factor and S/N of the marker were almost the same when seamless capillary and dovetailed capillary were compared. The dovetailed capillary was applied to cyclodextrin modified capillary zone electrophoresis. The control of the EOF enabled us to control both the resolution and the migration order of the enantiomers. The migration time was also controllable and, therefore, the best condition between separation and migration time could be determined by controlling the EOF. Partial filling affinity electrokinetic chromatography with a protein used as a chiral selector was also studied. The migration of the pseudo-stationary phase was controllable by EOF, and detection of the solute at 214 nm was possible. Therefore, the EOF-controlled dovetailed capillary has great potential to expand the application of the separation technique.