1.1 This practice covers information relating to sampling, calibration and validation of X-ray fluorescence instruments for elemental analysis, including all kinds of wavelength dispersive (WDXRF) and energy dispersive (EDXRF) techniques. This practice includes sampling issues such as the selection of storage vessels, transportation, and sub-sampling. Treatment, assembly, and handling of technique-specific sample holders and cups are also included. Technique-specific requirements during analytical measurement and validation of measurement for the determination of trace elements in samples of petroleum and petroleum products are described. For sample mixing, refer to Practice D5854. Petroleum products covered in this practice are considered to be a single phase and exhibit Newtonian characteristics at the point of sampling. 1.2 Applicable Test Methods—This practice is applicable to the XRF methods under the jurisdiction of ASTM Subcommittee D02.03 on Elemental Analysis, and those under the jurisdiction of the Energy Institute’s Test Method Standardization Committee (Table 1). Some of these methods are technically equivalent though they may differ in details (Table 2). (A) Nadkarni, R. A., Guide to ASTM Test Methods for the Analysis of Petroleum Products and Lubricants, 2nd edition, ASTM International, West Conshohocken, PA, 2007. 1.3 Applicable Fluids—This practice is applicable to petroleum and petroleum products with vapor pressures at sampling and storage temperatures less than or equal to 101 kPa (14.7 psi). Use Practice D4057 or IP 475 to sample these materials. Refer to Practice D5842 when sampling materials that also require Reid vapor pressure (RVP) determination. 1.4 Non-applicable Fluids—Petroleum products whose vapor pressure at sampling and sample storage conditions are above 101 kPa (14.7 psi) and liquefied gases (that is, LNG, LPG, etc.) are not covered by this p