How to certify reference materials: by voting or by exact weights

Abstract

The problems of using reference materials (RM) of oil and petroleum products humidity is discussed for different programs of certification: according to accuracy of the preparation procedure (RM-PP), according to the results of the interlaboratory studies (RM-INTERLAB) and using reference methods (RM-RM). Similar NIST samples (SRM 2271 and 272) were used for comparison. The problem of using CO-INTERLAB for control the accuracy of standard methods is the absence of the true value, this task is not even raised. "Accuracy control" has a different emphasis in this situation: RM-INTERLAB allow to select, "voting by majority" among the general population of the laboratory and cut the others. Therefore, their main application is qualification tasks. This approach is basically incorrect for analyzers. In the case of RM-PP and RM-RM, the main problem is the difference in the composition of real samples and ideal matrices of RM’s. Their main application is the control the accuracy of the analyzers in the absence of interfering influences. The "cheap" RM’s production technologies do not allow the omprehensive control of the real oil samples. The complication of oil technologies and the use of heavy oils in refining could provide the progress in RM’s.