ASTM D2896 for base number of petroleum products by potentiometric perchloric acid titration
18. Report of Result for Back Titration
18.1 Report the result as follows:
Base Number by Back Titration
(Test Method D2896 - Procedure A or B) = Result
19. Precision and Bias
19.1 Preliminary Precision - Preliminary repeatability of this test method using a silver/silver chloride reference electrode has been found to be equal to or better than using the reference electrode specified in the current test method. Preliminary results appear in Table 1. The subcommittee will continue to determine the precision within the next five years.
19.2 Procedure A (120 mL):
19.2.1 The precision of this test method as determined by statistical examination of interlaboratory results is as follows (see Note 15 and Note 17):
19.2.1.1 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 only in one case in twenty:
NOTE 19 - Since there were insufficient data from the 1986 cooperative study to determine the precision for the back titration procedure for used oils, the back titration precision data are those obtained in the 1972 study. A new cooperative study is planned to determine the back titration precision using modern instrumentation.
19.2.1.2 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 only in one case in twenty:
NOTE 20 - The ranges of base number values for which these precision values were established are given in Appendix X1.
19.2.2 Bias - This procedure in this test method for measuring base numbers has no bias because the base numbers can be defined only in terms of the test method.
19.3 Procedure B (60 mL):
19.3.1 The precision of this test method as determined by statistical examination of interlaboratory results is as follows:
(see Note 15 and Note 17):
19.3.1.1 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 only in one case in twenty:
19.3.1.2 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 only in one case in twenty:
19.3.2 Bias - This procedure in this test method for measuring base numbers has no bias because the base numbers can be defined only in terms of the test method.
20. Keywords
20.1 base number; perchloric acid; petroleum products; potentiometric titration