ASTM D5863 Nickel, Vanadium, Iron, and Sodium in Crude Oils and Residual Fuels
ASTM D5863 Standard Test Methods for Determination of Nickel, Vanadium, Iron, and Sodium in Crude Oils and Residual Fuels by Flame Atomic Absorption Spectrometry
20. Calculation
20.1 For Test Method A, calculate the concentration of each analyte in the sample using the following equation:
analyte concentration, mg/kg = (C x V x F)/W
where:
C = concentration of the analyte in the test solution (corrected for the concentration determined in the reagent blank), µg/mL,
V = volume of the test solution, mL,
F = dilution factor, volume/volume or mass/mass, and
W = sample mass, g.
20.2 For Test Method B, calculate the concentration of each analyte in the sample using the following equation.
analyte concentration, mg/kg = C x F
where:
C = concentration of the analyte in the test solution, mg/kg, and
F = dilution factor, volume/volume or mass/mass.
21. Report
21.1 Report the following information:
21.1.1 Report concentrations in mg/kg to two significant figures.
22. Precision and Bias
22.1 Precision - The precision of this test method was determined by statistical analysis on interlaboratory test results. For Test Methods A and B, six cooperators participated in the interlaboratory study. Seven samples (four residual oils and three crude oils) comprised the test set. One residual oil was NIST SRM 1618. One crude oil was NIST SRM 8505.
22.1.1 Repeatability - The difference between two test results, obtained by the same operator with the same apparatus under constant operating conditions on identical test materials would, in the long run, in the normal and correct operation of the test method, exceed the values in Table 3 and Table 4 only in one case in twenty.
22.1.2 Reproducibility - The difference between two single and independent results, obtained by different operators working in different laboratories on identical test materials, would in the long run, in the normal and correct operation of the test method, exceed the values in Table 5 and Table 6 only in one case in twenty.
22.2 Bias - Bias was evaluated from results obtained on two NIST samples. For Test Method A, the means of the reported values for V and Ni do not differ from the corresponding expected values by more than the repeatability of the test method. For Test Method B, the mean of the reported values for V does not differ from the corresponding expected value by more than the repeatability of the test method, and the mean of the reported values for Ni is higher than the expected value by an amount approximately equal to twice the repeatability of the test method. Standard reference materials for Fe and Na are not available, so bias was not determined for these elements.
23. Keywords
23.1 atomic absorption spectrometry; AAS; iron; nickel; sodium; vanadium
