Express analyzers of motor fuels: the problems of metrological support

Abstract

The problems of identifying counterfeit motor fuels in real conditions are highlighted. It is noted that the use of express analyzers of motor fuels does not provide the necessary level of control over the accuracy and reliability of measurement results of the parameters of the fuel under study. The problems of metrological support of express analyzers of motor fuels based on near-infrared spectroscopy are considered. The method is based on the rejection of classical spectroscopic approaches in favor of complex multidimensional mathematical models, and the result of the analysis is a forecast; the usual metrological approaches do not work here, since quantitative analysis is replaced by some kind of qualitative analysis. The category of uncertainty is replaced by the category of reliability, which is much less developed. In this situation the usual accuracy control procedures are insufficient. For express analyzers based on the principles of dielmetry and near-infrared spectroscopy, the identification of counterfeit fuel turned out to be approximately the same: the addition of 8–10 % vol. of the counterfeit component practically does not change the measurement results. When the operations with a mathematical model is not allowed (it is the intellectual property of developers) some simple approaches to the assessment of metrological characteristics is proposed. This approach allows the metrologist or the user to verify the relevance of the program model for specific grades of motor fuel. A study of domestic express analyzers based on the principles of measuring the dielectric permittivity of fuels has been carried out. The ability of express analyzers of both types to identify counterfeit fuel is evaluated.