Reference number
ISO 1693:1976
ISO 1693:1976
© ISO 2025
International Standard
ISO 1693:1976
Cryolite, natural and artificial — Determination of fluorine content — Modified Willard-Winter method
Edition 1
1976-09
1976-09
ISO 1693:1976
6309
Publicado
(Edición 1, 1976)
Esta publicación se revisó y confirmó por última vez en 2020.
Por lo tanto, esta versión es la actual.
Resumen
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.
Informaciones generales
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Estado: PublicadoFecha de publicación: 1976-09Etapa: Norma Internacional confirmada [90.93]
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Edición: 1Número de páginas: 6
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Comité Técnico :ISO/TC 226ICS :71.060.50
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