Codes & Standards - Purchase
ISO 1693:1976
Cryolite, natural and artificial -- Determination of fluorine content -- Modified Willard-Winter method
SKU: iso_006309_101681
Published by ISO
Publication Year 1976
1 Edition
6 pages
Product Details
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.