Indirect spectrophotometric determination of mesalazine via chromate-1,5-diphenyl carbazide complex

Abstract EN

A simple and rapid indirect spectrophotometric method for the determination of mesalazine is developed.

The method is based on the rapid reduction of known large amount of chromate CrO4 -2 in the presence of mesalazine in acidic medium of 2N H2SO4.

The excess amount of chromate is measured after it's reaction with 1,5-diphenylcarbazide which finally gives a pink-violet, water soluble and stable complex, which exhibit a maximum absorption at 546 nm.

Beer's law is obeyed in the concentration range from (5-900) μg of mesalazine in a final volume of 25 ml (0.2-36 ppm) with a molar absorbtivity of 1×105 l.mol-1.cm-1, Sandell's sensitivity index of 0.0015 μg .cm-2 and relative standard deviation ± 0.0848 to ± 0.3155 depending on the concentration level.

The proposed method is applied successfully to the assay of mesalazine in its pharmaceutical prepearation (capsules).