UOP 700-70

This is a method for determining free sulfur in petroleum distillates and liquefied petroleum gas (LPG) using the AC polarograph. The lower limit of detection is a function of the solubility of the sample in the supporting electrolyte and toluene mixture; in most cases it is 0.1 ppm. The method appears to be free of interferences by constituents found in distillates, e.g., peroxides, phenols and other sulfur compounds. Mercaptans interfere only when present at high concentration, such as 1000 times the free sulfur content.