Quantitative analysis of ibuprofen in pharmaceuticals and human control serum using kinetic spectrophotometry

The aim of this work was to develop a new kinetic spectrophoto- metric method for the determination of ibuprofen in pharmaceutical formula- tions. Ibuprofen was determined in an acidic ethanolic medium by monitoring the rate of appearance of 1-nitroso-2-naphthol, resulting from the displacement by ibuprofen of Co(III) from the tris(1-nitroso-2-naptholato)cobalt(III) com- plex. The optimum operating conditions regarding reagent concentrations and temperature were established. The tangent method was adopted for construc- ting the calibration curve, which was found to be linear over the concentration range 0.21-1.44 and 1.44-2.06 µg ml -1 . The optimized conditions yielded a theoretical detection limit of 0.03 µg ml -1 based on the 3.3 S0 criterion. The interference effects of the usual excipients of powdery drugs, foreign ions and amino acids on the reaction rate were studied in order to assess the selectivity of the method. The developed procedure was successfully applied for the rapid determination of ibuprofen in commercial pharmaceutical formulations and hu- man control serum. The unique features of this procedure are that the determi- nation can be performed at room temperature and the analysis time is short. The newly developed method is simple, inexpensive and efficient for use in the analysis of a large number of samples.