ENANTIOSEPARATION OF NONSTEROIDAL ANTIINFLAMMATORY DRUGS BY CAPILLARYELECTROPHORESIS USING MIXTURES OF ANIONIC AND UNCHARGED BETA-CYCLODEXTRINS AS CHIRAL ADDITIVES

Nine nonsteroidal anti-inflammatory drugs (NSAIDs) were enantioseparat ed by capillary electrophoresis using an anionic cyclodextrin derivati ve (sulfobutyl ether beta-cyclodextrin or carboxymethyl-beta-cyclodext rin) in combination with a neutral cyclodextrin as chiral additives to a pH 3 phosphoric acid-triethanolamine buffer. In the presence of a n egatively charged cyclodextrin, the analytes were given an appropriate mobility but relatively low enantioselectivities were generally obtai ned when such a cyclodextrin was the only selector added to the buffer . The addition of an uncharged cyclodextrin, such as the native beta-c yclodextrin or one of its derivatives (dimethyl-, trimethyl- and hydro xypropyl-beta-cyclodextrin), to this kind of buffer containing an anio nic cyclodextrin, was found to give rise to considerable improvement i n chiral resolution for all compounds studied. Resolution and analysis time were optimized by varying the nature and concentration of the tw o cyclodextrins. The best compromise was usually achieved by the simul taneous addition of sulfobutyl ether beta-cyclodextrin and trimethyl-b eta-cyclodextrin. Under optimum conditions, the enantiomers of all NSA IDs examined could be completely separated (most often with resolution values higher than 5) in short analysis times (generally lower than 1 5 min).