Active standard | Published: 01/09/1976

ISO 1693:1976

Cryolite, natural and artificial — Determination of fluorine content — Modified Willard-Winter method
(Cryolithe, naturelle et artificielle — Dosage du fluor — Méthode de Willard-Winter modifiée)

Available languages: English, French

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Detail information

Designation: ISO 1693:1976

Publication date: 01/09/1976

Pages: 6

Country: International technical standard

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Anotation

Description / Abstract: Specifies the determination for natural and synthetic materials having a molar ratio sodium fluoride/aluminium trifluoride between 3 and 1,7 approximately. The principle consists in fusion of a test portion with sodium carbonate, separation of fluorine by distillation with sulphuric acid or perchloric acid. Titration with thorium nitrate solution in presence of sodium alizarinsulphonate/methylene blue as indicator. Alternatively, the thorium nitrate titration may be made using only sodium alizarinsulphonate, the end-point being*spectrophotometrically determined at 525 nm.

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