15. Report
15.1 For results equal to or greater than 10 mg/kg, report the sulfur result to the nearest mg/kg. For results less than 10 mg/kg, report the sulfur results to the nearest tenth of a mg/kg. State that the results were obtained according to this Test Method D7620.
16. Quality Control
16.1 Confirm the performance of the instrument or the test procedure by analyzing a quality control (QC) sample (8.6) after each calibration and at a frequency in accordance with local site requirements.
16.1.1 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.
16.1.2 When there is no QC/QA protocol established in the testing facility, Appendix X1 may be used as the QC/QA system.
17. Precision and Bias
17.1 Precision - The precision of this test method as determined by statistical examination of interlaboratory test results using Practice D6300 is as follows.
NOTE 5 - The following precision data were developed in a 2008 interlaboratory cooperative test program. Six laboratories analyzed 14 sample sets each of gasoline, gasoline with 10 % ethanol, diesel, biodiesel (B100), and jet fuel. Their sulfur concentration ranges were from 4.0 mg/kg to 830 mg/kg.
17.1.1 Repeatability - The difference between two test results obtained by the same operator with the same apparatus under constant operating conditions on identical test material would, in the long run, in the normal and correct operation of the test method, exceed the following values in only 1 case in 20, where x = the average of the two test results.
17.1.2 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, in the normal and correct operation of the test method, exceed the following values in only 1 case in 20, where x = the average of two test results.
17.1.3 For repeatability and reproducibility estimates at several sulfur levels, see Table 3.
17.2 Bias - The bias of this test method by analysis of National Institute of Standards and Technology (NIST) standard reference materials (SRMs) containing known levels of sulfur in gasoline and diesel has not been determined.
17.2.1 Relative Bias - Relative bias to Test Method D5453 has not been determined.
18. Keywords
18.1 diesel; gasoline; total sulfur analysis; UV-fluorescence detection