ISO 4274:1977
Urea for industrial use — Determination of biuret content — Flame atomic absorption and photometric absorption methods
Reference number
ISO 4274:1977
Edición 1
ISO 4274:1977
Retirada (Edición 1, 1977)


Applicable to products having contents of equal to or more than 0.05 % (m/m) (with flame atomic absorption) or 0.1 % (m/m) (with fotometric absorption). Covers the formation of a complex between biuret and copper(II) sulphate in alkaline medium. Fixation of this complex on an anion exchange resin. Elution of Cu first with a potassium nitrate solution and then with a nitric acid solution. Flame atomic absorption: aspiration of the solution into an acetylene-air flame and measurement of the absorption of the 325-nm line emitted by a copper hollow-cathode lamp; or by photometric absorption: formation of a coloured complex between Cu and zinc dibenzyldithiocarbamate, extraction with carbon tetrachloride and measurement at a wavelength of about 435 nm. Has also been approved by the IUPAC.

Informaciones generales

  •  : Retirada
     : 1977-10
    : Retirada de la Norma Internacional [95.99]
  •  : 1
     : 6
  • ISO/TC 47
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