Numéro de référence
ISO 3329:1975
ISO 3329:1975
© ISO 2024
ISO 3329:1975
Nitrate d'ammonium à usage industriel — Dosage des composés soufrés — Méthode par réduction et titrimétrie
Edition 1
1975-07
1975-07
Annulée
Résumé
Applicable to products the content of which, expressed as sulphate, is equal to or more than 0.0005 % (m/m). Heating of a test portion in the presence of sodium carbonate, in a fume-cupboard, until the ammonium salts have been eliminated (about 300 °C). Reduction of the sulphureous residue to sulphides by a mixture of hydriodic acid and hypophosphorus acid. Absorption of the hydrogen sulphide evolved in a mixture of sodium hydroxide solution and acetone. Titration of the sulphide with standard volumetric mercury(II) acetate solution in the presence of dithizone as indicator. A typical apparatus for reduction and distillation is shown in a figure.