PMID: 18962019Jan 1, 1977

Indirect determination of fluoride by EDTA back-titration of lanthanum

Talanta
K MuraseN Shiraishi

Abstract

Semimicro to macro amounts of fluoride ion (0.4-100 mg) are determined rapidly and accurately by precipitation with an excess of lanthanum at pH 2.5-2.8 by digestion on a water-bath, cooling to room temperature, addition of excess of EDTA and back-titration of the excess with zinc solution to the Xylenol Orange end-point at ph 5.8-5..9. Large amounts of chloride, acetate and perchlorate, and small amounts of sulphate and silicate do not interfere, but phosphate does. This method is much superior to the usual thorium nitrate titration method and can be applied after preliminary separation of fluorine by steam distillation or pyrolysis.

Related Concepts

Acetate
Edetic Acid
Fluorides
Fluorine
Lanthanum
Inorganic phosphate
Serum Bactericidal Test
Zinc
Xylenol
Perchlorate

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