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

The new, single-isomer, octakis(2,3-diacetyl-6-sulfato)-gamma-cyclodextrin (ODAS-gamma CD) has been used for the capillary electrophoretic separation of the enantiomers of weak acids, mostly nonsteroidal anti-inflammatory age nts, 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-gamma CD, while those of the strongly binding analytes passed a local minimum due to the combined, opposing effects of complexation and ionic strength-induced m obility depression. Separation selectivity decreased as the concentration o f ODAS-gamma CD was increased, in agreement with the predictions of the cha rged resolving agent migration model. Good peak resolution could be obtaine d with ODAS-gamma CD in less than 10-20 min for all the weak acid analytes tested. (C) 2000 John Wiley & Sons, Inc.