This test method provides for the precise measurement of the total sulfur content of gasolines and diesels with minimal sample preparation and analyst involvement. The typical time for each analysis is two to three minutes.

Knowledge of the sulfur content of diesel fuels, gasolines, and refinery process streams used to blend gasolines is important for process control as well as the prediction and control of operational problems such as unit corrosion and catalyst poisoning, and in the blending of products to commodity specifications.

Various federal, state, and local agencies regulate the sulfur content of some petroleum products, including gasoline and diesel fuel. Unbiased and precise determination of sulfur in these products is critical to compliance with regulatory standards.

1.1 This test method covers the determination of total sulfur by monochromatic, wavelength-dispersive X-ray fluorescence (MWDXRF) spectrometry in single-phase gasolines, diesel fuels, and refinery process streams used to blend gasoline and diesel, at concentrations from 2 mg/kg to 500 mg/kg. The precision of this test method was determined by an interlaboratory study using representative samples of the liquids described in 1.1 and 1.2. The pooled limit of quantitation (PLOQ) was estimated to be 4 mg/kg.

Volatile samples such as high-vapor-pressure gasolines or light hydrocarbons might not meet the stated precision because of the evaporation of light components during the analysis.

1.2 Gasoline samples containing oxygenates may be analyzed with this test method provided the matrix of the calibration standards is either matched to the sample matrices or the matrix correction described in Annex A1 is applied to the results. The conditions for matrix matching and matrix correction are provided in the Interferences section (Section 5).

1.3 Gasolines and diesels with sulfur contents above 500 mg/kg can be analyzed after dilution with appropriate solvent (see 5.2). The precision and bias of sulfur determinations on diluted samples has not been determined and may not be the same as shown for neat samples (Section 15).

1.4 When the elemental composition of the samples differ significantly from the calibration standards used to prepare the calibration curve, the cautions and recommendation in Section 5 should be carefully observed.

1.5 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.

This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific hazard information, see 3.1.