Spectrophotometric Determination of Paracetamol in Pharmaceutical Preparations Via Arsenazo III - Cerium(III) Reaction


A simple, rapid, accurate and precise spectrophotometric method is proposed for determining paracetamol in pure form and in its pharmaceutical preparations. The method is based on oxidation-reduction reaction between paracetamol and cerium(IV) ion, then reaction of cerium(III) with arsenazo III reagent in acidic medium to produce a green-blue complex which is stable, water soluble and has a maximum absorption at 654 nm with a molar absorptivity of 1.1702105 l.mol-1.cm-1. Beer’s law is obeyed in the concentration range from 1 to 14 g paracetamol in a final volume of 25 ml. The proposed method has been applied successfully to determine paracetamol in pharmaceutical preparations.