Error and Uncertainty in the Results of Chemical Analysis

Abstract

Twenty years have elapsed since the concept of uncertainty was elaborated, which provided the basis not only for the INC-1 Recommendations but for some other international documents as well. However, the use of this concept presents considerable difficulties in some cases. In the submitted paper, starting from the basic metrological postulates, we have analyzed the concept and compared it with the concept based on the notion of the measurement error in order to reveal possible reasons for the above-mentioned difficulties. The analysis demonstrates the inconsequence of the concept of the uncertainty of measurement and contradictions between some of its postulates and the basic postulates of metrology. The cryometric determination of the degree of purity of benzoic acid and acetanilide were taken as examples to demonstrate the numerical equality between the estimated uncertainty and the error on the one hand. On the other hand, it was also shown that a distinction should be made between the uncertainty of the result of measurements and the uncertainty of the measurand. Drawbacks of the uncertainty concept were outlined, and it was shown that the elimination of these drawbacks would favor the application of the concept in particular cases.