Spectrophotometric Determination of Isoniazid in Pharmaceutical Preparations Using Oxidative Coupling Reaction with 2,4-dinitrophenylhydrazine

A spectrophotometric method is proposed to determine isoniazid using oxidative coupling reaction. The proposed method depends on adding the oxidizing agent potassium periodate to the reagent solution 2,4-dinitrophenylhydrazine. Different optimum conditions are studied and explained based on various experiments and tests. The wavelength is (406) nm. Beer's law within the concentration (0.2-40) µg/ml, and with a molar absorptivity value of 0.2482 × l.mol -1 .cm -1 , while the recovery was (98.46%), and the relative standard deviation did not exceed 1.34. The method was successfully applied for the determination of isoniazid in its pharmaceutical preparations (medicine tablets).