Application of MBTH and Sulphanilic acid for the Quantitative Spectrophotometric Determination of Diacerein in bulk and formulations

Two simple, rapid and sensitive spectrophotometric methods have been proposed for the determination of diacerein in bulk and pharmaceutical formulations. Method A was based on the oxidation of 3-methylbenzothiazolin-2-one hydrazone (MBTH) by ferric chloride followed by its coupling with the drug in acidic medium. Method B was based on the reaction of Sulphanilic acid with sodium nitrite in acid medium to form diazonium ion, which is coupled with diacerein in basic medium to form azodyes. The colored complexes produced in the above two methods shows maximum absorbance at 670 nm (Method A) and 505 nm (Method B). Under optimized experimental conditions, Beer’s law is obeyed over concentration ranges of 1-5 and 2-10 μg/ml for methods A and B respectively. All the methods have been applied to the determination of diacerein in pharmaceutical dosage forms. Results of analysis are validated statistically.