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

This paper reports a continuous flow-based spectrophotometric method for th e determination of paracetamol in pharmaceuticals. Dilute samples containin g paracetamol are continuously hydrolysed in an alkaline medium, using a ho usehold 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 mug ml(-1) and the system obeys Beer's law from 0.6 to 20 mug ml(-1). Repeatability was checked by ca lculating the R.S.D. for 11 standard solutions containing a paracetamol con centration of 4 mug ml(-1) each and found to be 1.8%. The proposed method w as validated by determining paracetamol in various pharmaceutical preparati ons with average R.S.D. of 2.4%. (C) 2000 Elsevier Science B.V. All rights reserved.