An evaluation of some methods for the determination of fluoride in potable waters and other aqueous solutions

Abstract

Five spectrophotometric procedures for the determination of fluoride in water have been evaluated with respect to reproducibility, sensitivity, range, stability of coloured products and of reagents, specificity and effect of temperature. The thorium nitrate titration is briefly discussed, and the use of the Orion fluoride-ion electrode for pF measurement has also been investigated. Various samples of water containing natural or added fluoride have been analysed by four of the spectrophotometric methods, and the results compared with those obtained by titration and with the electrode. The electrode is shown to be less susceptible than the colorimetric methods to interference from other ions in solution, and it gives theoretical recoveries of fluoride added to several drinking water supplies.