Selective colorimetric determination of paracetamol by means of an indophenol reaction

Abstract

The spontaneous oxidation of alkaline mixtures of p-aminophenol and phenol with molecular oxygen to form indophenol has been made the basis of a colorimetric procedure for the determination of paracetamol via its hydrolysis product, p-aminophenol. The hydrolysis product of phenacetin, p-phenetidine, does not undergo this reaction. Several other active ingredients with which paracetamol is often formulated have been shown not to interfere. Total paracetamol and phenacetin can be determined by an indophenol reaction after hydrolysis and oxidation with acidified hypochlorite.