Spectrophotometric Determination of Salicylamide and Paracetamol in Biological Samples and Pharmaceutical Formulations by a Differential Kinetic Method

A rapid, simple and sensitive spectrophotometric method is presented for the determinations of salicylamide and paracetamol in mixture. The method is based on their complexation and oxidation reactions by Fe ion. Two sets of conditions were established such that in one set of conditions only salicylamide reacts with Fe ion, but in the other set of conditions both of the salicylamide and paracetamol are oxidized by Fe ion in the presence of 1,10-phenantroline. In both sets the reactions can be monitored spectrophotometrically by measuring the absorbance of the produced copmplexes at 510 nm. The data were evaluated by proportional equations. The method allowed the determination of salicylamide and paracetamol at concentrations between 2.0 – 300 μg mL and 0.50 10 μg mL with relative standard deviations of 2.58% and 3.47%, respectively. The method was applied to the determination of salicylamide and paracetamol in human serum and pharmaceutical formulations.