1.1 The purpose of this standard is to indicate the method to be used for the determination of total sulfur in petroleum products, with concentrations greater than 0.002% (m/m). Annex A describes a special method of analysis that allows the determination of sulfur in concentrations less than 5 pp m. In the general method, sulfur is determined in the form of sulfate, by acidimetry, with a titrated solution of sodium hydroxide; A gravimetric variant (precipitation in the form of barium sulfate) is described in Annex B. 1.2 The direct combustion procedure (see Chapter 7) is applicable to the analysis of products such as gasoline, kerosene, naphtha and other liquid products that can be burned satisfactorily by direct combustion. The blending procedure (see Chapter 8) is applicable to the analysis of diesel fuels and distilled fuel oils, high sulfur petroleum products, and many other products that cannot be burned satisfactorily by direct combustion. It is not applicable to heavy waste such as residual fuel oil, asphalt and tar. 1.3 Phosphorus compounds generally present in commercial gasoline do not affect the determination. A correction is given for the small amounts of acid resulting from the combustion of lead-based anti-knock additives in gasoline. Appreciable contents of elements capable of forming acids and bases, from various sources, interfere when the titration method is used, since no correction is planned in that case.