Spectrophotometric determination of fluoride a comparative study and a suggestion for evaluating photometric data

Summary Attempts were made to develop a method for fluoride determination using the demasking principle; the result was negative. Using the method of bleaching, ferric-sulfosalicylate, ferric-tiferronate, titanium-chromotropic acid and zirconium-alizarin coloured systems have been thoroughly investigated and compared for use as reagents for fluoride determination. Ferric-sulfosalicylate system has been proved to be the best. A new method of comparing photometric data has been suggested. Error in fluoride determination by ferric-sulfosalicylate method according to the method calculation suggested is between 1.80 percent and 4.60 percent, when the fluoride concentration is from 16 to 40 ppm. The method gives reproducible results when the fluoride concentration is in the range of 0.8 ppm to 4.0 ppm.