A limit test for <i>p</i>-chloroacetanilide and other impurities in paracetamol and phenacetin using thin-layer chromatography

Abstract A thin-layer chromatography procedure is described suitable as a limit test for p-chloroacetanilide in paracetamol and phenacetin. The sample is chromatographed on silica gel together with a standard using the solvent mixture cyclohexane: acetone: diisobutylketone: methanol: water (100:80:30:5:1) and detection is by irradiation with ultraviolet light 253.7 mμ followed by examination in light of wavelength 365 mμ. The procedure may be used to limit the p-chloroacetanilide content of tablets containing paracetamol or phenacetin. Other possible impurities in paracetamol and phenacetin are also detected and may be limited by similar procedures.