Pyrocatechol Violet in Pharmaceutical Analysis Part II. A Spectrophotometric Method for the Determination of Paracetamol in Pure and in Pharmaceutical Dosage Forms

A spectrophotometric method for the selective determination of paracetamol based on its reaction with pyrochatechol violet under basic conditions to form an ion-pair complex is described. The absorption maximum of the coloured ion-pair formed is observed at 652 nm and the molar absorptivity is 4.54 x10^-3l mol^-1 cm^-1. Beer's law is obeyed over the concentration range 0.5-34.0 μg ml^-1, while that obtained using Ringbom method is in the range 3.5 -32.0 μg ml^-1. There is no interference from common additives, excipients and commercial drugs present in their formulations suggesting a highly selective procedure compared with others. Statistical analysis of the obtained results showed that there is, no significant difference and absence of any systematic error in the method compared with the official one. The method is simple, rapid and convenient and was applied successfully to the determination of paracetamol in pure and in its dosage forms compared with the official method.