Capillary electrophoretic separation of the enantiomers of weak acids in a high pH background electrolyte using the new, single-isomer, octakis(2,3-diacetyl-6-sulfato)-γ-cyclodextrin as chiral resolving agent

The new, single-isomer, octakis(2,3-diacetyl-6-sulfato)-γ-cyclodextrin (ODAS-γCD) has been used for the capillary electrophoretic separation of the enantiomers of weak acids, mostly nonsteroidal anti-inflammatory agents, in a high pH background electrolyte where all the acidic analytes were fully dissociated. The anionic effective mobilities of the weakly-binding anionic analytes decreased with increasing concentration of ODAS-γCD, while those of the strongly binding analytes passed a local minimum due to the combined, opposing effects of complexation and ionic strength-induced mobility depression. Separation selectivity decreased as the concentration of ODAS-γCD was increased, in agreement with the predictions of the charged resolving agent migration model. Good peak resolution could be obtained with ODAS-γCD in less than 10-20 min for all the weak acid analytes tested.