适用于F含量等于或大于0.5 mg/kg的产品。规定了在磷酸介质中通过水蒸气蒸馏将元素从试样中分离出来的方法。在pH值为4.6的缓冲介质中，与组合试剂茜素络合剂/硝酸镧形成蓝色络合物。加入丙酮以增加络合物的稳定性和灵敏度。在约600 nm波长下对配合物进行光度测量。

Applicable to products the F content of which is equal to or more than 0.5 mg/kg. Specifies the separation of the element from a test portion by steam distillation in a phosphoric acid medium. Formation of a blue-coloured complex with a combined reagent alizarin complexone/lanthanum nitrate in a buffered medium at the pH of 4.6. Addition of acetone to increase the stability of the complex and the sensitivity. Photometric measurement of the complex at a wavelength of about 600 nm.