Abstract
Colorimetric determination of acetanilide in mixed pharmaceutical preparations was examined, and a new method with high accuracy and selectivity was established. Acetanilide was hydrolysed by refluxing with hydrochloric acid to produce aniline which reacts with sodium nitrate in an acid medium to form a diazonium compound. Coupling of the resulting diazonium compound with β-diethylaminoethyl-α-naphthylamine oxalate produced red dye. The diazo dye had an absorption maximum at 560 mμ. Interference by the presence of acetaminophen, nicotinoyl-4-aminoantipyrine, antipyrine, and aminopyrine can be eliminated by chloroform extraction in an acid medium. This method of determination is not interfered by the presence of phenacetine acetylsalicylic acid, caffeine, diphenhydramine hydrochloride, chlorophenilamine maleate, ethoxybenzamide, ephedrine hydrochloride, etc.
