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(l1) ammine sulphate. The complex is extracted with chloroform and treated with diethyldithiocarbamate solution, whereupon another copper(l1) complex (Amax. 430 nm) is formed. Beer's law is followed over the concentration ranges 6-60 pg ml-1 for flufenamic acid and 6-48 pg ml-1 for mefenamic acid.

A spectrodensitometric method is described for the determination of the components of two analgesic mixtures. For the first mixture (paracetamol-ascorbic acid-caffeine-phenylephrine), the pharmaceutically active components were separated from each other and closely related degradation products and impurities on high-performance thin-layer chromatography (F254) plates using methylene chloride-ethyl acetate-ethanol-formic acid (3.5 + 2 + 4 + 0.5) and methylene chloride-ethyl acetate-ethanol (5 + 5 + 1) as the developing systems. The other mixture (phenazone-phenacetin-caffeine) was separated efficiently from the degradation products using the same plates and acetonitrile-chloroform (1 + 1) as the mobile phase. The proposed method was used to determine these mixtures in commercial tablets.

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