Spectrophotometric Determination of Oxymetazoline Hydrochloride Via Oxidative Coupling Reaction with 4-Aminoantipyrine in the Presence of Potassium Periodate

A simple spectrophotometric method is developed for the determination of oxymetazoline hydrochloride (OMCl) as pure and in its pharmaceutical preparations. The method is based on the oxidative coupling reaction of OMCl with 4-aminoantipyrine (4-A.A.P) in the presence of potassium periodate as oxidizing agent in an alkaline medium to produce a coloured water soluble product that is stable and has a maximum absorption at 480 nm. Beer's law is obeyed in a concentration range 20 -400μg OMCl/20 ml with a molar absorptivity of 5.34 x 10 1.mol.cm, a relative error of -0.50 to -1.47% and a relative standard deviation of ± 0.36 to ± 1.58%, depending on the concentration level. The optimum conditions for full colour development are described and the proposed method was applied successfully to the assay of OMCl in two pharmaceutical preparations.