Investigation of chiral resolution using displacement interactions with polymer networks in capillary affinity zone electrophoresis

The effect of displacers on the resolution of the stereoisomers folinic acid, mandelic acid and N-benzoylalanine at physiological pH using capillary affinity zone electrophoresis is described. Bovine serum albumin (BSA) is used as a run buffer additive to incorporate stereoselectivity into the system, while salicylates exhibiting different affinities for BSA are added to the electrolyte for the displacement studies. The salicylate, alpha-resorcylic acid, was found to increase retention and stereoselectivity for the samples, while other displacers exhibited a negative effect on chiral resolution. Changes in effective mobility and resolution of stereoisomers using different displacers added to the run buffer did not correlate with reported equilibrium binding constants (K-b) for the displacer-BSA complexes. Protein-wall interactions were minimized using a combination of dextran in the supporting electrolyte and capillaries derivatized with polyacrylamide. Dextran played a secondary role by improving resolution. The results indicate that displacers may be used to optimize chiral separations in affinity capillary electrophoresis. In addition, the use of albumin as a pseudostationary phase may be used to screen drug-displacer interactions with BSA.