This International Standard specifies a method for the determination of the sulfur content of liquid petroleum products, additives for petroleum products, and semi-solid and solid petroleum products that are either liquefied by moderate heating or soluble in organic solvents (see 4.1) of negligible or accurately known sulfur content. The method is applicable to products or additives having sulfur contents in the range 0,001 % (m/m) to 2,50 % (m/m); higher contents can be determined by appropriate dilution. Other elements do not interfere at concentrations anticipated in the materials subject to this analysis.

High concentrations of phosphorus or chlorine [typically above 3 % (m/m)] can cause bias in the sulfur result by absorbing Zr-Lα and S-Kα to different extents. It is necessary in these cases to carry out studies to determine whether this potential interference is significant.

When larger amounts of molybdenum are present (typically above 50 mg/kg to 100 mg/kg), increased background radiation and spectral overlap with the sulfur signal can occur. It is necessary in these cases to inspect the relevant spectral regions, for example, to investigate the significance of this potential source of bias.