Abstract
A simple and sensitive spectrofluorometric method was developed for the quantitative determination of some β-blockers, namely arotinolol, atenolol and labetalol as hydrochloride salts. The method is based on the reaction of these drugs as n-electron donors with the fluorogenic
reagent 9,10-dimethoxy-2-anthracene sulfonate (DMAS) as π-acceptor in acidic medium. The obtained ion-pairs were extracted into chloroform and measured spectrofluorometrically at 452 nm after excitation at 385 nm. The fluorescence intensity-concentration plots are rectilinear over the ranges
of 0.5-5 μg · ml1, 1.0-11.0 μg · ml1 and 0.6-6.4 μg · ml1 for labetalol, atenolol and arotinolol, respectively. The different parameters affecting the reaction pathway were thoroughly studied and optimized. No
interference was observed from the common pharmaceutical excipients. The proposed method was successfully applied to the analysis of tablets and the results were statistically compared with those obtained by reference methods. The method was further extended to the in vitro determination
of the drugs in spiked human plasma, the% recoveries (n = 3) ranged from 96.98 ± 1.55 to 98.28 ± 2.19. A proposal of the reaction pathway was postulated.