karbala journal of pharmaceutical sciences

A simple, accurate and sensitive spectrophotometric method for the determination of Methyldopa in pure and pharmaceutical preparations has been developed .The proposed method uses Thiamine Hydrochloride as anew chromogenic reagent . The method is based on the oxidative coupling reaction of Methyldopa with Thiamine Hydrochloride with potassium periodate in neutral media to form orange water soluble dye product , that has a maximum absorption at λmax 480 nm . Linear calibration graph was in the range of (1.00–25.00) µg.ml-1 with molar absorptivity of (0.53 ×104 L.mol-1.cm-1) ,a sandall sensitivity of (4.49 ×10-5 µg.cm-2) , correlation coefficient of (0.9997) , detection limit (0.38 µg.ml-1) and the relative standard deviation of RSD% (0.97) . The method was applied successfully for the determination of Methyldopa in pharmaceutical preparations and the value of recovery % was better than (102%)