适用于F含量大于0.003%（m/m）的产品。在压力下用硫酸溶解试验部分。在（150 1）°C的温度下用硫酸蒸馏分离氟。蒸馏按照ISO 1693中描述的方法进行。在pH值在4.5和4.6之间的氟和茜素络合剂/氯化镧试剂之间形成蓝色络合物。添加丙酮以增加氟络合物的稳定性和灵敏度。在大约620nm的波长下对配合物进行分光光度测量。也得到了IUPAC的批准。

Applicable to products having F contents of more than 0.003 % (m/m). Dissolution of a test portion by attack by sulphuric acid under pressure. Separation of the fluorine by distillation at a temperature of (150 1) °C by sulphuric acid. The distillation is carried out by the method described in ISO 1693. Formation of a blue coloured complex between fluorine and alizarin complexone/lanthanum chloride reagent at a pH between 4.5 and 4.6. Addition of acetone to increase the stability and sensitivity of the fluorine complex. Spectrophotometric measurement of the complex at a wavelength of about 620 nm. Has also been approved by the IUPAC.