International Standard
ISO 1693:1976
Cryolite, natural and artificial — Determination of fluorine content — Modified Willard-Winter method
Reference number
ISO 1693:1976
ISO 1693:1976
Edition 1
1976-09
1976-09
© ISO 2024
International Standard
ISO 1693:1976
6309
Published
(Edition 1, 1976)
This standard was last reviewed and confirmed in 2020.
Therefore this version remains current.
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.
General information
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Status: PublishedPublication date: 1976-09Stage: International Standard confirmed [90.93]
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Edition: 1Number of pages: 6
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Technical Committee :ISO/TC 226ICS :71.060.50
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