1.1 These test methods cover the determination of nickel, vanadium, iron, and sodium in crude oils and residual fuels by flame atomic absorption spectrometry (AAS). Two different test methods are presented. 1.2 Test Method A, Sections 7-12-Flame AAS is used to analyze a sample that is decomposed with acid for the determination of total Ni, V, and Fe. 1.3 Test Method B, Sections 13-17-Flame AAS is used to analyze a sample diluted with an organic solvent for the determination of Ni, V, and Na. This test method uses oil-soluble metals for calibration to determine dissolved metals and does not purport to quantitatively determine nor detect insoluble particulates. 1.4 The concentration ranges covered by these test methods are determined by the sensitivity of the instruments, the amount of sample taken for analysis, and the dilution volume. A specific statement is given in Note 3. 1.5 For each element, each test method has its own unique precision. The user can select the appropriate test method based on the precision required for the specific analysis. 1.6 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. Specific warning statements are given in Notes 1, 2, 5 and 6. 1.7 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.