ISO 14596 Petroleum products - Determination of sulfur content - Wavelength-dispersive X-ray fluorescence spectrometry
9 Procedure
9.1 General
For some products, e.g. residual oils, it can be necessary to deviate from the provisions given in 9.2 and 9.3, that is, to increase the maximum temperature from 100 °C to 120 °C in order to obtain a homogenous sample. In these cases, this deviation shall be mentioned in the test report (Clause 13, item e).
9.2 Samples with sulfur contents between 0.1 % (m/m) and 2.5 % (m/m)
Weigh 20.00 g +/- 0.01 g of the sample for analysis (see Note in Clause 6) into a flask (5.4) and add 5.00 g +/- 0.01 g of the zirconium solution A (4.4). Homogenize thoroughly, with heating if necessary, to a maximum temperature of 80 °C. After cooling to 18 °C to 28 °C, proceed in accordance with 8.2 and calculate the gross count ratio, R.
9.3 Samples with sulfur contents between 0.001 0 % (m/m) and 0.1 % (m/m)
Weigh 20.00 g +/- 0.01 g of the sample to be analysed (see Note in Clause 6) into a flask (5.4) and add 2.00 g +/- 0.01 g of the zirconium solution B (4.5). Homogenize thoroughly, with heating if necessary, to a maximum temperature of 80 °C. After cooling to 18 °C to 28 °C, proceed in accordance with 8.3 and calculate the net count ratio, RO.
10 Calculation
Read the sulfur content from the calibration curves constructed in 8.2 or 8.3. If the sulfur content is above 2.5 % (m/m), dilute the sample with white oil (4.1) and repeat the procedure specified in 9.2.
NOTE Many modern instruments contain a microprocessor that retains the calibration curve and produces a digital readout.
