Integrated pervaporation/detection for the determination of fluoride in pharmaceuticals

A selective dynamic method for the determination of fluoride in pharmaceuticals based on the integration of pervaporation and potentiometric detection in a laboratory-made module is proposed. The analyte was continuously converted into volatile trimetylfluorosilane by reaction with hexamethyldisilazane, injected into a donor stream and accepted in a basic buffer solution after pervaporation. The method thus developed has a determination range between 1.5 and 200 mg l-1, precision (expressed as R.S.D.) of 3.4%, and has been applied to the determination of fluoride in different pharmaceutical products, with yields ranging between 90.6 and 100.3%. B.V.