1.1 This test method covers the determination of total sulfur in petroleum and petroleum products that are single-phase and either liquid at ambient conditions, liquefiable with moderate heat, or soluble in hydrocarbon solvents. These materials can include diesel fuel, jet fuel, kerosine, other distillate oil, naphtha, residual oil, lubricating base oil, hydraulic oil, crude oil, unleaded gasoline, gasoline-ethanol blends, biodiesel (see Note 2), and similar petroleum products. NOTE 1—Oxygenated fuels with ethanol or methanol contents exceeding the limits given in Table 1 can be dealt with using this test method, but the precision and bias statements do not apply (see Appendix X3). NOTE 2—For samples with high oxygen contents (>3 weight %) sample dilution as described in 1.3 or matrix matching must be performed to assure accurate results. 1.2 Interlaboratory studies on precision revealed the scope to be 17 mg ⁄ kg to 4.6 mass %. An estimate of this test method’s pooled limit of quantitation (PLOQ) is 16.0 mg ⁄ kg as calculated by the procedures in Practice D6259. However, because instrumentation covered by this test method can vary in sensitivity, the applicability of the test method at sulfur concentrations below approximately 20 mg/kg must be determined on an individual basis. An estimate of the limit of detection is three times the reproducibility standard deviation, and an estimate of the limit of quantitation2 is ten times the reproducibility standard deviation. 1.3 Samples containing more than 4.6 mass % sulfur can be diluted to bring the sulfur concentration of the diluted material within the scope of this test method. Samples that are diluted can have higher errors than indicated in Section 16 than non-diluted samples.