Spectrophotometric and High Performance Liquid Chromatographic Methods for the Determination of Dapsone in a Pharmaceutical Preparation

The detailed investigation of a sensitive and selective spectrophotometric method for the determination of dapsone; based on the oxidative coupling reaction of dapsone drug with pyrocatechol in the presence of potassium periodate in acidic medium to form an intense, stable, purple-red coloured water-soluble dye, which shows a maximum absorption at 509 nm. Beer's law obeyed over the range of 10-500 μg /25 ml, i.e,0.4-20 ppm with a molar absorptivity of 1.05×10l.mol.cmand Sandell's sensitivity index of 0.0235 μg.cm ,a relative standard deviation of ±2.60 to ±1.05%; and limit of detection, (LOD) of 0.1735 μg.ml.; and (LOQ) of 0.5785μg.ml. And the method does not require temperature control or solvent extraction. HPLC technique has been also developed for the measurement of dapsone. The analysis was achieved on a C18 column using water and acetonitrile in the ratio of 50:50 (V:V) as a mobile phase at a flow rate equals to 0.5 ml / min. and the detection was done spectrophotometrically at 297 nm. A linear relationship is obeyed over the range 0.5-20 ppm with a relative standard deviation (RSD) ±1.53 to ±0.83% and relative error -0.3 to +1.1 %. Both methods were applied successfully to the assay of dapsone in pharmaceutical preparation (Tablet).