Spectrophotometric Determination of Diclofenac sodium Using 2,4-dinitrophenylhydrazine in Pure Form and Pharmaceutical Preparations

A simple and sensitive spectrophotometric method is described for the determination of diclofenac sodium (DCL), in pure form and pharmaceutical formulations. The method is based on the oxidation of 2,4-dinitrophenylhydrazine (2,4-DNPH) and coupling of the oxidized product with DCL in alkaline medium to give intensively colored chromogen which exhibits maximum absorption (λmax) at 600 nm, and the concentration of DCL was determined spectrophotometrically. The optimum reaction conditions and other analytical parameters were evaluated. In addition to classical univariate optimization, modified simplex method (MSM) has been applied in optimization of the variables affecting the color producing reaction.Beer’s law is obeyed in the concentration range of 0.5-40 μg.mL-1 with molar absorptivity of 2.0994×104 L.mol-1.cm-1. The limit of detection was found to be 0.020 μg.mL-1 and the Sandellʼs sensitivity value was 0.0152 μg.cm-2. The proposed method was successfully applied to the determination of DCL in pharmaceutical preparations.