ASTM D4045 Standard Test Method for Sulfur in Petroleum Products by Hydrogenolysis and Rateometric Colorimetry
12. Quality Assurance/Quality Control (QA/QC)
12.1 Confirm the performance of the instrument and the test procedure by analyzing a control (QC) sample.
12.1.1 When QA/QC protocols are already established in the testing facility, these may be used when they confirm the reliability of test result.
12.1.2 When there is no QA/QC protocol established in the testing facility, Appendix X1 may be used as the QA/QC system.
12.2 Users of this test method are advised that in contractual agreements, one or more of the contracting parties can and may make Appendix X1 a mandatory practice.
13. Precision and Bias
13.1 The precision of this test method as obtained by statistical analysis of interlaboratory test results is as follows:
13.1.1 Repeatability - The difference between successive 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 this test method, exceed the following values only in one case in twenty (see Table 1).
where
X = average value of two results, mg/kg.
13.1.2 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 following values only in one case in twenty (see Table 1).
NOTE 2 - One laboratory conducted a statistical evaluation by analyzing the same sample (with a nominal sulfur concentration of 0.2 ppm), using multiple technicians and the same instrumentation, with and without the humidifier gas wash bottle installed, and determined that results were statistically equivalent for both precision and accuracy at the 95 % confidence interval. Results of the statistical evaluation are available from ASTM Headquarters.
13.2 Bias - The bias of this test method cannot be determined since an appropriate standard reference material containing trace sulfur levels in petroleum products is not available.
14. Keywords
14.1 rateometric colorimetry; sulfur