Spectrophotometric and high performance liquid chromatographic methods for the determination of dapsone in a pharmaceutical preparation

الملخص EN

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 × 104l.mol-1.cm-1 and Sandell's sensitivity index of 0.0235 μg.

cm-2, a relative standard deviation of ±2.60 to ±1.05 % ; and limit of detection, (LOD) of 0.1735 μg.ml-1 ; and (LOQ) of 0.5785μg.

ml-1.

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).