Simultaneous determination of propacetamol and paracetamol by derivative spectrophotometry

A first-derivative spectrophotometric method for the simultaneous determination of propacetamol hydrochloride (PRO) and paracetamol (PA) is described. Measurements are made at the zero-crossing wavelengths at 242.0 for PRO and 239.0 nm for PA. The calibration graphs were linear up to 20.0 and 15.0 mg l−1 of PRO and PA, respectively, the limits of quantification were 0.75 and 0.46 mg l−1. The possible interfering effects of other substances were studied. The method was applied to determining the stability of PRO in ethanolic solutions and in glucose and saline parenteral solutions.