The Colorimetric Determination of Phenacetin in Tablet Mixtures

Abstract

Phenacetin may be quantitatively converted to nitrophenetidine by nitration and subsequent saponification with sodium hydroxide. The nitrophenetidine thus formed is soluble in alkaline solution and may be determined colorimetrically at 445 mμ. The method may be applied to samples containing 1 to 5 mg. of phenacetin. This method possesses several advantages over existing methods in that it is simple, sensitive and accurate and does not require the tedious separation of caffeine when applied to the determination of phenacetin in aspirin, phenacetin and caffeine mixtures. Recovery data of phenacetin in these mixtures are given. A simple and rapid procedure for the analysis of the components of aspirin, phenacetin and caffeine is also described.