Résumé
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.
Informations générales
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État actuel: PubliéeDate de publication: 1976-09Stade: Norme internationale confirmée [90.93]
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Edition: 1Nombre de pages: 6
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Comité technique :ISO/TC 226ICS :71.060.50
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