LIQUID-CHROMATOGRAPHIC PROCEDURE FOR THE EVALUATION OF BETA-BLOCKERS IN PHARMACEUTICALS USING HYBRID MICELLAR MOBILE PHASES

A reversed-phase chromatographic procedure with a micellar eluent is p roposed for the determination of several beta-blockers (acebutolol, at enolol, carteolol, celiprolol, labetalol, metoprolol, nadolol, oxpreno lol, propranolol, and timolol) in pharmaceutical formulations (tablets , capsules and ophthalmic solutions). A study is shown on the chromato graphic behaviour of these drugs with mobile phases containing sodium dodecyl sulphate (0.075-0.15 M) and propanol (0-15%, v/v), at differen t pH values (3-7). The excellent correlation between log of the octano l-water partition coefficient and log of capacity factor, for the ten drugs in mobile phases of SDS and propanol, suggested that the differe nce in retention among them was mainly governed by their hydrophobicit y. A mobile phase of 0.15 M SDS-15% propanol at pH 3 permitted the elu tion of the beta-blockers in less than 15 min. The recoveries were usu ally in the 96-103% range, and the variation coefficients were below 2 .5%. The results were compared with those obtained with hydro-organic eluents of methanol-phosphate buffer.