Reference number
ISO 1693:1976
© ISO 2024
International Standard
ISO 1693:1976
Cryolite, natural and artificial — Determination of fluorine content — Modified Willard-Winter method
Edition 1
1976-09
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Published (Edition 1, 1976)
This publication was last reviewed and confirmed in 2020. Therefore this version remains current.

ISO 1693:1976

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Format
CHF 42
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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

  • Status
     : Published
    Publication date
     : 1976-09
    Stage
    : International Standard confirmed [90.93]
  • Edition
     : 1
    Number of pages
     : 6
  • Technical Committee :
    ISO/TC 226
    ICS :
    71.060.50 
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