ISO 5791:1978

Ammonium nitrate for industrial use — Determination of water content — Karl Fischer method

Describes a method applicable to products having water contents equal to or greater than 0,05 % (m/m). The principle of determination is based on the reaction of water with a solution of iodine and sulphur dioxide in a pyridine-methanol mixture (Karl Fischer reagent) which is standardized previously by titration of an exactly known mass of water. The end point of the reaction is then determined by means of the direct electrometric method.