Spectrophotometric Determination of Paracetamol by Reduction of 18-Molybdo-2-Phosphate Heteropoly Anion

A very simple, rapid and sensitive spectrophotometric method for paracetamol assay inpharmaceuticals based on the reduction of 18-molybdo-2-phosphate heteropoly complex wasdeveloped. Reaction of 18-molybdo-2-phosphate with paracetamol is very fast at roomtemperature. The stoichiometry of the reaction is 1:1. The molar absorptivity calculated forparacetamol was equal to that for heteropoly blue formed in the studied reaction and was of1.15×10^4 l mol^-1 cm^-1 at 820 nm. Beer`s law was followed for paracetamol concentrations from 0.3 to 7.5 μg ml^-1 (l = 1 cm). The detection limit of the method was 0.03 μg ml^-1 (l = 5 cm), and a relative standard deviation did not exceed 2.5 %. The method was successfully applied to the determination of paracetamol in pharmaceuticals.