Sequential spectrophotometric determination of paracetamol and p-aminophenol with 2,2′-(1,4-phenylenedivinylene) bis-8-hydroxyquinoline as a novel coupling reagent after microwave assisted hydrolysis

A new method to determine paracetamol and p-aminophenol in pharmaceutical products is presented. The purpose of this work is to introduce 2,2′-(1,4-phenylenedivinylene) bis-8-hydroxyquinoline (PBHQ) as a novel coupling agent. This developed method is based on the microwave assisted alkaline hydrolysis of paracetamol to p-aminophenol, which reacts in mildly alkaline medium with 2,2-(1,4-phenylenedivinylene)bis-8-hydroxyquinoline (PBHQ) as a novel coupling reagent. The formed product shows maximum absorbance at 650 nm with molar absorptivity = 3.4 × 104 l mol−1 cm−1 and the method was linear in the 0.44-5.5 mg l−1 concentration range. The detection limit value was found to be 0.09 μg ml−1. The stoichiometric composition of the dye is 2:1 (PAP:PBHQ). The effect of concentration of reactants and temperature on the coupling reaction was investigated. The proposed method is successfully adopted for the determination of paracetamol and p-aminophenol in various pharmaceutical preparations.