ISO 914:1977

The method is applicable to products having a total nitrogen content equal to or greater than 0.05 % (m/m). The principle consists in the conversion of the nitrogen present in a test portion to ammonia by means of nascent hydrogen. Distillation and absorption of the ammonia in an excess of standard volumetric sulphuric acid solution, and back-titration with a standard volumetric sodium hydroxide solution in the presence of an indicator. - Replaces ISO Recommendation R 914-1968.