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.
95.99 Withdrawal of Standard
May 27, 2002