ISO 20884 Petroleum products - Determination of sulfur content of automotive fuels - Wavelength-dispersive X-ray fluorescence spectrometry
4 Reagents
4.1 Dibutylsulfide, of nominal sulfur content 21.92 % (m/m), or dibutyldisulfide, of nominal sulfur content 35.95 % (m/m), used as a calibrating substance for sulfur.
Care should be taken due to volatility (see Annex A).
4.2 White oil (paraffinum perliquidum), for use as a blank solution, of high purity grade, with a sulfur content of less than 1 mg/kg. Check the blank solution prior to use with the spectrometer (5.1). A signal for sulfur shall not be detectable.
4.3 Methyl oleate, for use as a blank solution when FAME is analysed, with a sulfur content of less than 1 mg/kg. Check the blank solution prior to use with the spectrometer (5.1). A signal for sulfur shall not be detectable (i.e. the intensity shall be lower that the intensity equivalent to 1 mg/kg). Other oxygen-containing and sulfur-free blank solutions, such as octanol, can also be used.
5 Apparatus
5.1 Wavelength-dispersive X-ray fluorescence spectrometer, with the capability for measuring the count rates of the SK-L2,3 X-ray fluorescence radiation and the background radiation. Due to the inherently low background radiation produced by instruments utilizing monochromatic radiation for excitation, it is not mandatory to measure the background radiation when this type of instrument is used. The minimum requirements for the spectrometer are given in Table 1.
5.2 Analytical balance, capable of weighing to the nearest 0.1 mg.
