Rifampicin as a Novel Reagent in Spectrophotometric Assay of Paracetamol

Abstract

Rifampicin (REF), an antibiotic, is used for the first time to assay paracetamol in
bulk sample and in its dosage forms. The method is based on adding a known excess of Nbromosuccinimide oxidant to the p- aminophenol, resulting from acidic hydrolysis of
paracetamol. The residual oxidant is allowed to react with a fixed amount of Rifampicin
reagent and the absorbance of the resulting colored solution is measured at 475 nm(λ max
of REF). The absorbances measured are found to increase linearly with the amount of
paracetamol present originally in solution, Beer's law is obeyed over the concentration of
2.5 to 15 μg/ml paracetamol with a determination coefficient (R2) of 0.9979,molar
absorptivity factor of 4.63x 103 l.mol-1.cm-1,Sandell’s sensitivity index of 0.033 μg.cm-2 . The
quality control/assurance analytical variables such as limits of detection (LOD), limits of
quantification (LOQ) are also reported. The method is used successfully to assay
paracetamol in its pharmaceutical dosage form (tablets, syrup and injection).