ISO 994:1973

Potassium hydroxide for industrial use — Determination of iron content — 1,10- Phenanthroline photometric method

Describes a method that is more sensitive and more widely used than the 2,2′-bipyridyl method. It is applicable to products having iron contents equal to or greater than 0.3 mg/kg. The principle is based on the reduction of iron(III) by hydroxylammonium chloride, formation of a iron(II)/1,10-phenanthroline complex in a buffered system. Photometric measurement of the coloured complex at a wavelength of about 510 nm. – Cancels and replaces ISO Recommendation R 994-1969.