SELECTIVE SPECTROPHOTOMETRIC DETERMINATION OF P-AMINOPHENOL AND ACETAMINOPHEN

A specific spectrophotometric method was developed for the determinati on of p-aminophenol and acetaminophen. The method is based on the reac tion of p-aminophenol at ambient temperature with sodium sulphide in p resence of an oxidant to produce a methylene blue-like dye. Different oxidizing agents were tried, e.g. Ce(IV) and Fe(III). The colour devel oped within 10 min and remained stable for at least 3 h. The method wa s applied successfully to the determination of p-aminophenol in the pr esence of acetaminophen without prior separation. The method was also applied to the analysis of various commercially available acetaminophe n dosage forms and excellent recoveries were obtained comparable to th ose obtained by official procedures. The reaction product was isolated and a possible reaction mechanism was suggested.