Estimation of p-Aminophenol via Diazotization and Coupling Reaction with 4-Chlororesorcinol –Application on Paracetamol

A spectrophotometric method has been proposed for the direct determination of p-aminophenol (p-Amp). The method includes diazotisation of p-Amp using an excess of sodium nitrite and in the presence of hydrochloric acid, and after destroying the remaining nitrous acid by adding sulphamic acid, then the produced diazonium salt coupled with the reagent 4-chlororenocinol (4-Chlr) in an alkaline medium of sodium hydroxide to form a water-soluble azo dye that gives the highest absorption at the wavelength of 488 nm. The linear range that follows Beer's law was from 0.5 to 15 g/ml. The value of the molar absorptivity was 1.9905x104l/mol. cm. After investigation of the optimal conditions by studying all factors affecting the absorption of the formed azo dye. The method was applied to estimate paracetamol in its pharmaceutical preparations after hydrolysis process. The results of standard addition method proved that there is no interference by additives.