ISO 2221:1972

Formaldehyde solutions for industrial use — Limit test for inorganic chlorides

The method, as specified, is applicable when the required limit is not greater than 0,05 % and not less than 0,0005 %. If the required limit lies outside that range, the mass of the test portion should be changed. The principle of the test consists in comparison of the turbidity obtained by the addition of silver nitrate solution to a solution of the sample, in the presence of nitric acid, with that similary produced from a chloride solution of known concentration.