Indirect Spectrophotometric Method for Determination of Methyldopa in Pure and Pharmaceutical Formulation

Sensitive and accurate spectrophotometric method for the assay of methyldopa (MeD) as pure form and in it is formulations. The method was centred on the oxidation of methyldopa drug with Fe+2ions. The free Fe+2 ions react with 4,7-diphenyl-1,10-phenanthroline chromogenic reagent. In the method, the formed Ferron complex is colorimetrically can be monitored at 533 nm versus reagent blank. The linear relationship between various MeD concentrations versus absorbance for each concentration was in the range of 0.25-2.5 μg.mL-1 with molar absorptivity 1.3272x105 L.mol-1.cm-1 for the method. The determination coefficient (R2) was found to be 0.9902, and the limit of detection (LOD) and limit of quantification(LOQ) were 0.011μg.ml-1and 0.036 μg.ml-1, respectively. The percent recovery from 99.84% to 102.40 %. The suggested procedure could be used for the estimation of MeD in dosage forms (two types of tablets from two companies) with satisfactory results.