This method is for determining disulfide sulfur in gasoline,liquefied petroleum gas (LPG), and other light petroleumdistillates. Part A of the method, an acid stirring procedure, isused for low molecular weight disulfides usually found in LPG andfor distillates that do not contain tertiary disulfides. Because ofits rapidity, the acid stirring procedure is recommended forroutine work where tertiary disulfides are not a factor. Part B ofthe method, an acid reflux procedure, is reserved for samplescontaining tertiary disulfides. This method is applicable tosamples containing a disulfide sulfur concentration of 10 mass-ppmor greater.