A colorimetric method for the determination of phenacetin and paracetamol. Part I. An automated procedure for the determination, in formulations, of phenacetin and paracetamol alone or in the presence of aspirin and codeine phosphate

Abstract

A rapid, automated, colorimetric method for the determination of phenacetin and paracetamol is described. The reaction of either compound with acidic hypochlorite followed by coupling with alkaline phenol produces a blue indophenol dye, which is measured spectrophotometrically. The method has been applied to tablets containing phenacetin or paracetamol, alone or in combination with aspirin and codeine phosphate, and to a granule formulation containing paracetamol. Standard procedures were used for the determination of aspirin and codeine phosphate.