ISO 20884:2011 specifies a wavelength-dispersive X-ray fluorescence (WDXRF) test method for the determination of the sulfur content of liquid, homogeneous automotive fuels from 5 mg/kg to 500 mg/kg, which have a maximum oxygen content of 3,7 % (m/m). This product range covers diesel fuels containing up to about 10 % (V/V) fatty acid methyl ester (FAME) and motor gasolines containing up to about 10 % (V/V) ethanol. Products with higher oxygen content show significant matrix effects, e.g. FAME used as biodiesel. Nevertheless, FAME may be analysed when the corresponding procedures are followed. Other products may be analysed with this test method. However, precision data for products other than those mentioned have not been established for ISO 20884:2011.