The principle of the method consists in fusion of a test portion with sodium carbonate. Separation of fluorine by distillation with sulphuric acid. Titration with thorium nitrate solution using 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  • Status :  Withdrawn
    Publication date : 1972-12
  • Edition : 1
    Number of pages : 5
  • :
    ISO/TC 47
  • 71.060.50

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