spectrophotometric method for determination of methyldopa in bure and pharmaceutical formulation based on oxidative coupling reaction

this study dealt with a simple, sensitive, and rapid spectrophotometric method to determine methyldopa (mdp) in bure form and it is pharmaceutical preparation (tablet) by using a new prepared organic reagent. the method is based on preparation a new organic reagent (schiff s base) and using it in oxidative coupling reaction with mdp in acidic medium in the presence of potassium periodate to produce a stable, water-soluble orang complex with the maximum absorption signal at 481 nm, beer s law is followed for standard mdp solutions in the range of 5.0-40 μg/ml with a negative deviation at concentrations higher than 40 μg/ml. the molar absorptivity and sandell᾽s sensitivity index values are 6.082×10^3 l.mol^-1.cm^-1 and 0.0347μg /cm^2 with relative standard deviation of rsd% less than 5%, detection 1 limit of 0.8937 μg.ml^-1 and correlation coefficient of 0.9979. two approaches were applied to determine the mdp amount in its pharmaceutical formulation (tablets), the first depending on regression equation and the second on the standard addition method. the results were obtained with sufficient precision and accuracy, with characterization of the prepared organic reagents and the product of oxidative coupling reaction by ft-ir-spectroscopy.