ISO 5397:1984, Leather -- Determination of nitrogen content and hide substance -- Titrimetric method

The principle consists in decomposition of a test portion by Kjeldahl method, distillation of the ammonia liberated, determination of the nitrogen content by titration of the ammonia with sulfuric or hydrochloric acid, using phenolphthalein as indicator. The method is applicable to all types of leather in all types of tannage. This title may contain less than 24 pages of technical content.