Petroleum products. Determination of sulfur content of automotive fuels. Wavelength-dispersive X-ray fluorescence spectrometry Petroleum, Petroleum products, Automotive fuels, Liquid fuels, Chemical analysis & testing, Determination of content, Sulfur, Gasoline, Diesel fuels, Fuel oil, Fuels, Oxygen, Esters (carboxylic), Methyl compounds, Fatty acids, X-ray fluorescence spectrometry, Spectroscopy, Fluorimetry, Wavelengths, Dispersion (waves)