ISO 23201:2015 sets out a wavelength dispersive X-ray fluorescence spectrometric method for the analysis of aluminium oxide for trace amounts of any or all of the following elements: sodium, silicon, iron, calcium, titanium, phosphorus, vanadium, zinc, manganese, gallium, potassium, copper, chromium and nickel. These elements are expressed as the oxides Na₂O, SiO₂, Fe2O₃, CaO, TiO₂, P₂O₅, V₂O₅, ZnO, MnO, Ga₂O₃, K2O, CuO, Cr₂O₃, and NiO on an un-dried sample basis. The method is applicable to smelting-grade aluminium oxide. The concentration range covered for each of the components is also given.