ISO 1693:1976

Cryolite, natural and artificial — Determination of fluorine content — Modified Willard-Winter method

Publication date: Sep 1, 1976

General information

Current stage: 90.93 Effective date: Nov 3, 2020

Originator: ISO

Owner: ISO/TC 226

Type: International Standard

ICS: 71.060.50

Languages: French English

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Scope

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.

Life cycle

NOW

PUBLISHED
ISO 1693:1976
90.93 Standard confirmed
Nov 3, 2020

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