ISO 2992:1974, Ammonium sulphate for industrial use -- Determination of iron content -- 2,2- Bipyridyl photometric method'

Applicable to Fe contents of equal to or more than 0.0001 % (m/m). The reaction bases on the reduction of iron(III) by hydroxylammonium chloride. Formation of the complex between iron(II) and 2,2'-dipyridyl in a buffered medium (pH value between 4.5 and 6). Photometric measurement of the coloured complex at a wavelength of about 522 nm. Has also been approved by the IUPAC. This title may contain less than 24 pages of technical content.