Synergistic chiral separations using the glycopeptides ristocetin A and vancomycin

The effectiveness of using a mixture of the chiral selectors vancomycin and ristocetin A to achieve chiral recognition was examined in this study. The results of using the mixed chiral selector vancomycin and ristocetin A in capillary electrophoresis were compared with the results of using each chiral selector alone. Chiral separations were carried out using a coated capillary column to suppress electroosmotic flow and minimize interactions with the capillary wall. We employed a countercurrent process where the solute reaches the detection cell window after the chiral selector has cleared the window, minimizing the background absorbance from the chiral selector and improving sensitivity. Using a mixture of vancomycin and ristocetin A, separations were achieved which often exceeded the resolving power of either chiral selector when used alone. The effect of voltage on resolution was also studied, and the optimal voltage was found to be between -5 and -8 kV.