A new colorimetric method for the determination of methyldopa

Abstract

A rapid and convenient method is described for the determination of methyldopa in pharmaceutical preparations. This is based on measuring the intensity of the orange colour, developed on reacting methyldopa with thiosemicarbazide in alkaline medium, at 490 nm. The colour obeys Beer's law in a concentration range of 2·0‐10 μ‐g ml−1. Since the catecholic function with free adjacent positions is required for the development of the colour, the method is highly specific.