SPECTROPHOTOMETRIC DETERMINATION OF FLUORIDE IN DOSAGE FORMS AND DENTAL PREPARATIONS

The method is based upon the reaction between fluoride ions and the co loured complex of Fe(III) with methyl salicylate to form the stable, c olourless hexaflouride complex of iron. The conditions of the method ( pH, time and combination ratio) were studied and a standard curve was obtained for 0.01-0.08 mg NaF ml(-1), at 525 nm. A study was conducted on interference with complexing anions of Fe(III), cations that react with fluoride ions and with common ingredients of dosage forms and de ntal preparations. The method was validated and the results showed goo d precision (100.16 +/- 2.33%) comparable with that of other analytica l methods. Good results were obtained in the spectrophotometric determ ination of fluoride ions in a stomatological gel and in a toothpaste.