ISO 1391-5:1981

Paraformaldehyde for industrial use — Methods of test — Determination of aldehyde content — Titrimetric method

The method is applicable to solid paraformaldehyde of aldehyde contents in the range 67 % (m/m) to 97 % (m/m). The principle consists in the reaction of aldehyde present in a test portion with neutralized sodium sulphite solution. Titration of the liberated sodium hydroxide with sulphuric acid solution using thymolphthalein as indicator. – This document has also been approved by the IUPAC.