ISO 6677:1983

Hexafluorosilicic acid for industrial use — Determination of available fluorine content — Potentiometric method after distillation

Covers a method consisting in separating the fluorine from a test portion by distillation in the presence of perchloric acid, followed by potentiometric titration of the distillate with lanthanum nitrate solution using a fluoride ion-selective electrode. Is applicable to products having total available fluorine contents in the range between 15 and 35 % (m/m).