ISO 1391-4:1976

Paraformaldehyde for industrial use — Methods of test — Part 4: Determination of water-insoluble matter

The principle of the procedure consists in the dissolution of a test sample in a highly diluted sodium hydroxide solution, filtration by using a tared filter crucible, drying of the residue at (100 2) °C. Determination of the in water insoluble substances by differences. – ISO 1391, Parts 1 to 4, replace ISO Recommendation R 1391-1970.