DETERMINATION OF ACETAMINOPHEN BY FLOW-INJECTION WITH ONLINE CHEMICALDERIVATIZATION - INVESTIGATIONS USING VISIBLE AND FTIR SPECTROPHOTOMETRY

A new FI/FTIR method for the determination of acetaminophen (paracetam ol, N-acetyl-p-aminophenol) involving on-line reaction is described. T he proposed method is based on the alkaline hydrolysis of the analyte to produce p-aminophenol and its oxidation reaction with potassium fer ricyanide to produce p-benzoquinone-monoimine which eventually oxidize s to form p-benzoquinone. The chemistry of the reaction was studied bo th, in the visible and IR regions of the spectrum and the method has b een developed by the application of flow-injection methodology. The re action was carried out in aqueous media and at room temperature. The m icro-flow version of the CIRCLE(R) IR accessory, which is compatible w ith aqueous solutions, was used. Measurements were carried out at the OH-phenolic deformation (1274.1 cm(-1)) and the aromatic ring mode (14 98.2 cm(-1)) infrared vibrations for the hydrolysis product, p-aminoph enol. The method was applied to the determination of acetaminophen in commercial tablets, and mean detection values of 512 and 491 mg were f ound at 1274.1 and 1498.2 cm(-1) respectively. (C) 1998 Elsevier Scien ce B.V.