ASTM D7111 Standard Test Method for Determination of Trace Elements in Middle Distillate Fuels by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES)
17. Report
17.1 Report element concentrations in mg/kg to two decimal places. If a concentration is determined to be below the detection limit (BDL) of the instrument, it should be identified as such (BDL) along with the determined detection limit for the element.
18. Quality Control
18.1 Confirm the performance of the instrument or the test procedure by analyzing a quality control (QC) sample (see 8.8).
18.1.1 If a suitable QC fuel sample is not available, prepare QC samples daily from the QC concentrate at different concentrations in the working range in the same manner described in 12.3.
18.1.2 When QC/quality assurance (QA) protocols are already established in the testing facility, these may be used when they confirm the reliability of the test result.
18.1.3 When there is no QC/QA protocol established in the testing facility, Appendix X2 can be used as the QC/QA system.
19. Precision and Bias
19.1 Precision - The precision of this test method was determined by the statistical examination of two interlaboratory studies. The first interlaboratory study involved eight laboratories and twelve fuel samples analyzed in duplicate (six diesel, three aviation jet, and three kerosine fuels spiked with organometallics at varied levels within the range of the method). The second interlaboratory study (a rerun of sodium only, using HDPE sample bottles) involved six laboratories and twelve fuel samples analyzed in duplicate (six diesel, three aviation jet, and three kerosine fuels spiked with organometallics at varied levels within the range of the test method). The precision determined is as follows:
19.1.1 Repeatability - The difference between successive results obtained by the same operator with the same apparatus under constant operating conditions on identical test material would, in the long run, in the normal and correct operation of the test method, exceed the values in Table 3 only in one case in twenty.
19.1.2 Reproducibility - The difference between two single and independent results obtained by different operators working in different laboratories on identical test material would in the long run, exceed the values in Table 4 only in one case in twenty. Calculated reproducibility (and repeatability) values for a 1.0 mg/kg result are shown in Table 5.
19.2 Bias - Since there are no accepted reference materials for determining bias for this test method, no statement on bias is being made.
20. Keywords
20.1 aviation turbine fuel; diesel fuel; elemental analysis; fuel; ICP; inductively coupled plasma atomic emission spectrometry; internal standard; middle distillate fuels; trace elements
