Spectrophotometric Dertermination of Mesalazine by 8-Hydroxyquinoline and N-(1-naphthyl)ethylenediamine dihydrochloride Reagents in Bulk and Capsule Dosage Forms

Two simple and sensitive visible spectophotometric methods have been developed for the quantitative determination of mesalazine (MEZ) in bulk drug and pharmaceutical preparation (capsules). The proposed methods are based on oxidative coupling reaction of mesalazine with 8-hydroxyquinoline (method A) and N-(1-naphthyl)ethylendiamine (N-NED) (method B) in the presence of sodium periodate as oxidizing agent in alkaline medium to form coloured products, exhibiting maximum absorptions at 644 nm and 543 nm, respectively. Beer's law is obeyed in the concentrations range of 10-300 and 10-180 g /25ml with molar absorptivity of 1.7223104 and 0.6545104 l.mol-1cm-1, respectively. The relative error ranges between -0.4% to +0.16% and - 0.9% to - 0.31% with relative standard deviation of 1.31% to 0.39% and 0.88% to 0.32% for methods A and B, respectively. The optimum conditions for full colour development are described and the proposed methods are applied successfully to the assay of MEZ in pharmaceutical preparation (capsules).