Numéro de référence
ISO/R 849:1968
ISO/R 849:1968
© ISO 2024
ISO/R 849:1968
Acide phosphorique à usage industriel — Dosage du fer — Méthode spectrophotométrique au 2,2'-bipyridyle
Edition 1
1968-10
1968-10
Annulée
Résumé
Applicable to products having Fe contents of more than 0.001 % (m/m). Preliminary hydrolysis of polyphophate acids by prolonged boiling in the presence of hydrochloric acid. Reduction of iron(III) by means of hydroxylammonium chloride. Formation of the iron(II)-2,2'-dipyridyl complex in the presence of ammonium acetate at pH of 3.1 and a temperature of 75 °C (under the test conditions the phosphate ions do not interfere). Spectrophotometric measurement of the coloured complex at a wavelength of about 522 nm.