Determination of fluoride in natural waters by ion-selective electrode potentiometry after co-precipitation with aluminium phosphate.
The most effective conditions for masking aluminium in the determination of mug/1. levels of fluoride in water by ion-selective electrode potentiometry after co-precipitation with aluminium phosphate have been re-examined. The effectiveness of citrate for masking aluminium increases with pH, and up to 1.5 x 10(-2)M aluminium can be masked quantitatively at pH 8.5. Fluoride (5-100 mug in 500 ml of sample solution) is quantitatively co-precipitated at pH 4.7 with approximately 90 mg of aluminium phosphate. After dissolution of the precipitate and adjustment of the solution to pH 8.5 with TISAB, the fluoride content can be measured with a fluoride ISE. The method is simple and rapid, and is suitable for the determination of trace amounts of fluoride in various water samples.
Okutani
T
T
Department of Industrial Chemistry, College of Science and Technology, Nihon University, 1-8, Kanda-Surugadai, Chiyoda-ku, Tokyo, 101 Japan.
Tanaka
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C
Yamaguchi
Y
Y