Kinetic spectrophotometric method for the determination of ketoprofen in pharmaceuticals and biological fluids

A simple and sensitive kinetic method is described for the determination of ketoprofen in pure form, pharmaceuticals and biological fluids. The method utilizes an oxidative- coupling reaction based upon oxidation of 3-methyl-2-benzo-thiazolinone hydrazone hydrochloride (MBTH) with Ce(IV) in presence of HCl, where an electrophilic intermediate (diazonium salt of the reagent) is produced, then couples with ketoprofen yielding a highly colored condensation product. The absorbance is measured after 20 min at 605 nm. Calibration graph was linear over the concentration range of 1-8μg/mL with a minimum detection limit of 0.07 μg/mL. The proposed method was applied successfully to the determination of Ketoprofen in pharmaceutical preparations, plasma and urine. The % recoveries were 100.11 for pure form, 100.10 for tablets and gel, 100.0 for suspension and suppositories, 100.2 for capsules and ampoules and 99.79, 99.9 for plasma and urine. The results obtained were in good agreement with those obtained using reference methods for comparison.