ASTM D4629 Standard Test Method for Trace Nitrogen in Liquid Petroleum Hydrocarbons by Syringe/Inlet Oxidative Combustion and Chemiluminescence Detection
13. Quality Assurance/Quality Control (QA/QC)
13.1 Confirm the performance of the instrument and the test procedure by analyzing a quality control (QC) sample.
13.1.1 When QA/QC protocols are already established in the testing facility, these may be used when they confirm the reliability of test results.
13.1.2 When there is no QA/QC protocol established in the testing facility, Appendix X1 may be used as the QA/QC system.
13.2 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.
14. Precision and Bias
14.1 The precision of this test method as determined by statistical examination of interlaboratory results is as follows (see Table 1):
14.1.1 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 one case in twenty, where X = the average of the two test results.
14.1.2 Reproducibility - The difference between two single and independent test 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 one case in twenty, where X = the average of the two test results.
14.2 The bias of this test method cannot be determined since an appropriate standard reference material containing a known trace level of nitrogen in a liquid petroleum hydrocarbon is not available to form the basis of a bias study.