1.1 This International Standard specifies an analytical method for determining the fluorine content in uranium metal, uranium dioxide powder and pellets and solutions of uranyl nitrate. 1.2 The method can be used within the concentration range of 1 μg to 0,01 g of fluorine per gram of the sample. Impurity levels of up to 300 μg of boron and 3 000 μg of silicon, aluminium and iron in the final measured solution can be tolerated. Zirconium interferes seriously and should be absent. The applicability of the method to samples containing significant impurity levels can be confirmed by modifying the basic procedure.