ISO 2994:1974

Ammonium sulphate for industrial use — Determination of matter insoluble in water — Gravimetric method

Specifies the dissolution of a test portion in water; filtration under vacuum on the filter crucible, thorough washing of the filter crucible and detection of the absence of sulphates in the wash water by a barium chloride test, drying and weighing of the insoluble residue. Has also been approved by the IUPAC.