scope:

-Applies for the determination of natural and syntheticmaterials having a molar ratio sodium fluoride/aluminiumtrifluoride between 3 and 1, 7 approximately. The method isapplicable to products having an iron content equal to or greaterthan 0, 020 % (m/m). The principle consists in dissolution of atest portion by either alkaline or acid fusion. Reduction ofiron(III) with hydroxylammonium chloride, formation of the complexiron(II)-1, 10-phenathroline in a buffered medium at pH valuebetween 3, 5 and 4, 2. Photometric measurement of the colouredcomplex at a wavelength of about 510 nm. Applies ISO RecommendationR 1694- 1970.