Spectrophotometric method for the determination of flufenamic and mefenamic acids

A spectrophotometric method was developed for the determination of flufenamic and mefenamic acids both in the pure form and in pharmaceutical dosage forms. The method depends on their complexation with copper(II) ammine sulphate. The complex is extracted with chloroform and treated with diethyldithiocarbamate solution, whereupon another copper(II) complex (λmax. 430 nm) is formed. Beer's law is followed over the concentration ranges 6–60 µg ml–1 for flufenamic acid and 6–48 µg ml–1 for mefenamic acid.