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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)

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