Spectrophotometric Determination of Dapsone Using Phloroglucinol Azo Coupling Reagent

The research was concerned with a development of spectrophotometric method for the determination of trace amounts of dapsone. The method was based on the reaction of diazotized dapsone with phloroglucinol as azo coupling reagent in basic medium, to form an intense yellow coloured, water-soluble and stable azo-dye which showed a maximum absorption at 435 nm. Beers law is obeyed over the concentration range of 10-250 g/25ml, i.e.,0.4-10 ppm with molar absorptivity of 4.79 104 L.mol-1. cm-1 and Sandells sensitivity index of 0.005 g.cm-2, a relative error of + 0.12 to -0.34% and a relative standard deviation of 3.96 to 0.85% ; depending on the concentration level. The method does not require temperature control or solvent extraction and has been applied successfully to the determination of dapsone in pharmaceutical preparation (Tablet).