Continuous flow spectrophotometric determination of paracetamol in pharmaceuticals following continuous microwave assisted alkaline hydrolysis

This paper reports a continuous flow-based spectrophotometric method for the determination of paracetamol in pharmaceuticals. Dilute samples containing paracetamol are continuously hydrolysed in an alkaline medium, using a household microwave oven, to p-aminophenol, which reacts with o-cresol in 3.5 M NaOH. The blue derivative thus formed exhibits an absorbance maximum at 620 nm. The detection limit of the method is 0.2 μg ml−1 and the system obeys Beerʹs law from 0.6 to 20 μg ml−1. Repeatability was checked by calculating the R.S.D. for 11 standard solutions containing a paracetamol concentration of 4 μg ml−1 each and found to be 1.8%. The proposed method was validated by determining paracetamol in various pharmaceutical preparations with average R.S.D. of 2.4%.