EUROPIUM(III) ION PROBE SPECTROFLUOROMETRIC DETERMINATION OF DICLOFENAC SODIUM

A new method has been devised for the determination of diclofenac sodi um in bulk and in pharmaceutical preparations using Eu3+ ions as the F luorescent probe. The technique was built around the hypersensitive pr operty of the transitions of the fluorescent probe ion, Eu3+, at 616 n m. This is normally a forbidden transition, but the interaction with d iclofenac sodium, which contains a carboxylic group, makes the transit ion allowed and enhances the intensity of its fluorescence emission. T he Eu3+ fluorescence emission at 592 nm comes from a non-hypersensitiv e transition and is not affected by ligation. The intensity ratio, R, defined as I-592/I-616, was used as a measure of the percentage of bou nd probe ions. Diclofenac and Eu(III) forms a (1:1) molar complex. The relative stability constant of the complex was found to be 10(5). A l inear relationship between bound Eu3+ and the concentration of diclofe nac sodium was found for concentrations from 10 to 200 mu g ml(-1), wi th a recovery percentage of 100.22 +/- 2.27. The method shows a good a greement with a spectrophotometric method.