The polarographic behaviour of ketoprofen and assay of its capsules using spectrophotometric and voltammetric methods

The quantitative determination of ketoprofen using spectrophotometric and voltammetric methods are described. The spectrophotometric procedure depends upon the reaction of ketoprofen with N-bromosuccinimide (NBS). The residual reagent is then determined by formation of violet colour with 2,2-diphenyl-l-picryl hydrazine (DPPH(2)). The consumed NBS would correspond to ketoprofen. Beer's law is valid over the concentration range 5-80 mug/ml of the drug. Direct current (DC) polarography allows to study the reduction behaviour of ketoprofen at the dropping mercury electrode (DME) using different supporting electrolytes at different pH values. Direct current stripping voltammetry (DCSV) was used for the quantitative measurements of the drug. The calibration graph of peak current vs concentration was linear from 0.254 x 10(-2) to 0.254 mug/ml. In model solutions as little as 5.08 x 10(-4) ng/ml ketoprofen can be detected by DCSV. Both methods were applied successfully for the determination of ketoprofen either in pure or dosage forms.