ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Colorimetric determination of fluorides

E. Hlucháň and J. Mayer

Institut für Hygiene, Bratislava

Abstract: F- is detd. colorimetrically with methylthymol blue (I). The blue complex of I with Th⁴+ in HCl soln. at pH 2.6 has an absorption max. at 580 mμ. Addn. of F- changes the color to yellow owing to the formation of free I. The colorimetric reagent was prepd. by mixing 2.3 ml. of a soln. of 0.147 g. of Th(NO₃)₄.6H₂O in 250 ml. of H₂O with 2.7 ml. of a soln. of 0.190 g. of I in 250 ml. of H₂O. Both solns. were acidified with HCl to decolorization of 2,4-dinitrophenol. The proposed method is suitable for samples that have been steam distd. from H₂SO₄ soln. at 137-42° in an C₂H₂Cl₄ bath. I can be used also for titration of F- with standard Th(NO₃)₄ at pH 2-2.5.

Full paper in Portable Document Format: 178a569.pdf (in Slovak)

Chemical Papers 17 (8) 569–574 (1963)