ISO 1693-1976 天然和人造冰晶石 氟含量的测定 威拉德-温特尔的改进法

标准号：ISO 1693-1976
中文标准名称：天然和人造冰晶石 氟含量的测定 威拉德-温特尔的改进法
英文标准名称：Cryolite, natural and artificial; Determination of fluorine content; Modified Willard-Winter method
标准类型：D59
发布日期：1999/12/31 12:00:00
实施日期：1999/12/31 12:00:00
中国标准分类号：D59
国际标准分类号：73.060.40
适用范围：Specifies the determination for natural and synthetic materials having a molar ratio sodium fluoride/aluminium trifluoride between 3 and 1,7 approximately. The principle consists in fusion of a test portion with sodium carbonate, separation of fluorine by distillation with sulphuric acid or perchloric acid. Titration with thorium nitrate solution in presence of sodium alizarinsulphonate/methylene blue as indicator. Alternatively, the thorium nitrate titration may be made using only sodium alizarinsulphonate, the end-point being; spectrophotometrically determined at 525 nm.