Alkali-stable, high-pI isoelectric membranes have been synthesized from quaternary ammonium derivatives of cyclodextrins and poly(vinyl alcohol), and bifunctional cross-linkers, such as glycerol-1,3-diglycidyl ether. The new, high-pI isoelectric membranes were successfully applied as cathodic membranes in isoelectric trapping separations in place of the hydrolytically more labile, polyacrylamide-based cathodic isoelectric membranes, and permitted the use of catholytes as alkaline as 1 M NaOH. The new high-pI isoelectric membranes have shown excellent mechanical stability, low electric resistance and long life times, even when subjected to electrophoresis with current densities as high as 80 mA/cm2.

The third member of the family of single-isomer, sulfated gamma-cyclodextrins, the sodium salt of octakis(2,3-di-O-methyl-6-O-sulfo)-gamma-cyclodextrin has been synthesized, analytically characterized and used for the capillary electrophoretic separation of the enantiomers of nonionic, weak acid and weak base analytes in low-pH aqueous background electrolytes. Though octakis(2,3-di-O-methyl-6-O-sulfo)-gamma-cyclodextrin complexes less strongly with many of the analytes tested than the other members of the single-isomer, 6-O-sulfo gamma-cyclodextrin family, such as octa(6-O-sulfo)-gamma-cyclodextrin and octakis(2,3-di-O-acetyl-6-O-sulfo)-gamma-cyclodextrin, it offers excellent separation selectivities, often complementary to those of both the single-isomer, 6-O-sulfo beta-cyclodextrins and 6-O-sulfo gamma-cyclodextrins. Rapid, efficient enantiomer separations were observed for a large number of structurally diverse analytes in acidic aqueous background electrolytes.

The sodium salt of heptakis(2-O-methyl-6-O-sulfo)cyclomaltoheptaose (HMS), the second single-isomer, sulfated beta-CD carrying nonidentical substituents at all of the C2, C3, and C6 positions, has been synthesized, analytically characterized, and used for the capillary electrophoretic separation of the enantiomers of a group of 23 weak base analytes in acidic aqueous and methanolic BGEs. HMS interacted strongly with only about half of the analytes studied. The good separation selectivities and favorable normalized EOF mobilities allowed for rapid, efficient separation of the enantiomers of 19 of the 23 weak base analytes in the aqueous BGEs, often with separation selectivity values complimentary to those obtained with other single-isomer sulfated CDs. HMS did not prove to be as good a resolving agent in acidic methanolic BGEs as its counterpart, heptakis(2-O-methyl-3-O-acetyl-6-O-sulfo)cyclomaltoheptaose.

The enantiomers of 34 pharmaceutical weak-base analytes were separated by nonaqueous capillary electrophoresis in acidic methanol background electrolytes using the sodium salt of the new, single-isomer chiral resolving agent, octakis(2,3-O-dimethyl-6-O-sulfo)-gamma-cyclodextrin (ODMS). The effective mobilities, separation selectivities and peak resolution values of the weak-base analytes were determined as a function of the ODMS concentration in the 0-40 mM range and were found to follow the theoretical predictions of the charged resolving agent migration model (CHARM model) modified for ionic strength effects. Fast, efficient separations were achieved for both comparatively small and large enantiomers.

The sodium salt of heptakis(2-O-methyl-3-O-acetyl-6-O-sulfo)cyclomaltoheptaose (HMAS), the first single-isomer, sulfated beta-cyclodextrin carrying nonidentical substituents at all of the C2, C3, and C6 positions, has been synthesized, analytically characterized, and used for the capillary electrophoretic separation of the enantiomers of a group of 24 weak base pharmaceuticals in acidic aqueous and acidic methanolic background electrolytes. HMAS interacted more strongly with most of the analytes studied than heptakis(2,3-di-O-methyl-6-O-sulfo)cyclomaltoheptaose, but less strongly than heptakis(2,3-di-O-acetyl-6-O-sulfo)cyclomaltoheptaose, the respective analogs with identical substituents at the C2 and C3 positions. The good separation selectivities and favorable normalized electroosmotic flow mobilities allowed for rapid, efficient separation of the enantiomers of 19 of the 24 weak base analytes in the aqueous and methanolic background electrolytes. The trends in the effective mobilities and separation selectivities as a function of the HMAS concentration closely followed the predictions of the ionic strength-corrected charged resolving agent migration model.