Dye bleaching method for mesalazine determination in pure and pharmaceutical form

A simple, precise and new spectrophotometric procedure was developed for the estimation of mesalazine (Mesa) in its pharmaceutical form (PENTASA 500 mg) using dye bleaching method. The technique relies on oxidation of the drug using a mixture (KBr+KBrO3) in the presence of hydrochloric acid and malachite green dye, the final product of the reaction (greenish blue) is formed and measuring the absorbance at 618 nm. The concentrations obey Beer’s law for the compound ranged from (1-40) μg.ml−1. Sandel’s sensibility was 0.0819 µg/cm2, the ꞓ was 1.868247×103 (L/mol.cm). Detection limit and the quantitative limit were 0.00845 µg/ml, and 0.02561 µg.ml−1 respectively. Rec% was between (99.180-101.844) % and RSD% does not exceed 0.5986 ≥. The procedure was applied successfully for estimation of (Mesa) in its pharmaceutical form by the direct method and the method of single standard additions. The aim of the present study is to develop an economical and simple method for estimation of Mesa in pure and in pharmaceutical form. This procedure is based on the bleaching of dye.