The enantiomers of a series of basic drugs were separated in capillary zone electrophoresis (CZE) in phosphate buffers, pH 3, containing beta-cyclodextrin or one of its derivatives as chiral selectors and uncoated fused silica capillaries thermostated at 15 degrees C. The nature of the cationic component of the background electrolyte was found to have a significant influence on achiral resolution and peak symmetry. The best results were obtained with triethanolamine, which was then used to adjust the buffer pH in all further experiments. The effects on chiral resolution of the nature and concentration of cyclodextrin, of the addition of methanol, and of capillary temperature were studied. Maximum resolution was obtained at a particular cyclodextrin concentration for each analyte, depending on the affinity of the analyte for this cyclodextrin. On the basis of the results, the effects of methanol addition and temperature on enantiomeric resolution could be explained and predicted. Numerous chiral separations are presented and suggestions for the rapid optimization of CZE enantioseparations with cyclodextrin additives are given.

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SummaryHigh resolution could be achieved for the enantiomers of acidic drugs, namely, sulindac, fenoprofen, ketoprofen, warfarin, and hexobarbital, in a buffer of pH 3 by the simultaneous addition of uncharged and charged b-cyclodextrin derivatives. The interaction of the analytes with the anionic sulfobutyl ether P-cyclodextrin provides the analytes with an adequate electrophoretic mobility whereas the interaction with various neutral P-cyclodextrins generates high enantioselectivity. Five neutral cyclodextrins, the native P-cyclodextrin, as well as methyl-, dimethyl-, trimethyl-and hydroxypropyl-P-cyclodextrin, were tested to enhance the enantioselectivity of the electrophoretic system. High resolution values and the shortest analysis times for the five drugs tested were achieved in a buffer made of 100 mM phosphoric acid adjusted to pH 3 with triethanolamine and containing dimethyl-or trimethyl-0-cyclodextrin in addition to sulfobutyl ether P-cyclodextrin.

The aim of the present work was to investigate the separation of nonsteroidal anti‐inflammatory drugs (NSAIDs: niflumic acid, flufenamic acid, piroxicam, alclofenac, tiaprofenic acid, flurbiprofen, suprofen, ketoprofen, naproxen, indomethacin, carprofen, indoprofen, sulindac) in capillary electrophoresis (CE) using completely nonaqueous systems. The influence of different parameters such as nature and proportion of organic solvent (methanol, acetonitrile, 2‐propanol), apparent pH (ranging from 7 to 9) and temperature (ranging from 25 to 40oC) on selectivity and migration times were studied systematically in an uncoated fused‐silica capillary. A nonaqueous electrolyte made of 50 mM ammonium acetate — 13.75 mM ammonia in methanol proved to resolve 11 NSAIDs at 25oC and 13 NSAIDs at 36oC, both within 13 min and without a modifier besides the methanol itself. The same buffer containing 30% acetonitrile provides a satisfactory separation for 13 NSAIDs within 14 min at 25oC.