A simple, accurate, precise and sensitive colorimetric method for the determination of Paracetamol is described. This method is based on the formation of charge transfer complex with 4-chloro-7-nitro-2,1,3-benzoxadiazole (NBC-Cl) in acetone-aqueous medium [30% (v/v)]. The orange color product is measured at 475 nm for the formed complex. The optimization of various experimental conditions is described. Beer¢s law is obeyed in the range 0.5-3.5 mg ml-1, while that obtained applying Ringbom is 1.5-32.5 mg ml¬-1 . The molar absorptivity, Sandell sensitivity, detection and quantification limits are calculated. The results obtained showed good recoveries of 100.3± 1.1, with relative standard deviation of 0.98% for the formed colored complex. Application of the proposed method to representative pharmaceutical formulations is successfully compared to the official method.

Arabian J. Chem., 1, 1–8 (2008).