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ISO 1693:1976

Current Revision

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

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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.


SDO ISO: International Organization for Standardization
Document Number ISO 1693
Publication Date Not Available
Language en - English
Page Count
Revision Level
Supercedes
Committee ISO TC 47/SC 7
Publish Date Document Id Type View
Not Available ISO 1693:1976 Revision