ANALYSIS OF PILOCARPINE AND ITS TRANS EPIMER, ISOPILOCARPINE, BY CAPILLARY ELECTROPHORESIS

Capillary zone electrophoresis was used for the separation of pilocarp ine from its epimer, isopilocarpine, using coated fused-silica capilia ries of 20 cm x 25 mum I.D., 8 kV running voltage, migration buffer of 0.1 M sodium dihydrogenphosphate pH 8, detection at 217 nm and inject ion by electromigration. Injections of aqueous, acid and basic solutio ns were compared. Linearity of the signal for pilocarpine hydrochlorid e up to 200 mug ml-1 in 0.05 M hydrochloric acid was obtained, using n aphazoline nitrate as internal standard. Optimization of migration buf fer pH using coated silica capillaries of 50 cm x 50 mum I. D. showed that at pH 6.9 pilocarpine can be separated from isopilocarpine. Inclu sion of beta-cyclodextrin in the buffer allows full baseline separatio n of both epimers. The method was applied to the analysis of a commerc ial ophthalmic pilocarpine solution.