Spectrophotometric determination of Methyl dopa in pharmaceutical preparation via oxidative coupling organic reaction

Abstract

A simple, accurate and sensitive colorimetric method for the determination of Methyldopa in pure and pharmaceutical preparations has been developed .The proposed method uses ortho–Tolidine as anew chromogenic reagent .The method is based on the oxidative coupling reaction of Methyldopa with ortho–Tolidine with potassium periodate in neutral media to form orange water soluble dye product , that has a maximum absorption at ?max 480 nm . Linear calibration graph was in the range of (0.50–20.00) µg.ml^-1 with molar absorptivity of (1.37 ×10⁴ L.mol^-1.cm^-1) ,a sandall sensitivity of (1.73 ×10^-5 µg.cm^-2) , correlation coefficient of 0.9996 , detection limit (0.15 µg.ml^-1) and the relative standard deviation of RSD% (1.38) . The method was applied successfully for the determination of Methyl dopa in pharmaceutical preparations and the value of recovery% was better than (101.2%) .

Keywords: Spectrophotometric determination , Methyldopa, Pharmaceutical  preparations