ISO 2997:1974
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Phosphoric acid for industrial use -- Determination of sulphate content -- Method by reduction and titrimetry

This standard was last reviewed* in 2011.

*ISO standards are reviewed every five years.


Applicable to products having sulphate contents equal to or more than 0.0005 % (m/m). Analysis by reduction of the sulphate to sulphide by a mixture of hydriodic acid and hypophosphorus acid. Absorption of the hydrogen sulphide evolved in a mixture of acetone and sodium hydroxide solution. Titration with a standard volumetric solution of mercury(II) acetate in the presence of dithizone as indicator. Has also been approved by the IUPAC.


  • Document published on: 1974-11-01
    Edition: 1 (Monolingual) ICS: 71.060.30
    Status: Published Stage: 90.93 (2011-10-13)
    TC/SC: ISO/TC 47 Number of Pages: 3
  • Revises: ISO/R 847:1968

  • No corrigenda or amendments available

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