Development of express method of microgravimetric determination of actual resins in petrols

A new approach is proposed for a quick, simple assessment of one of the quality indicators of gasoline - the concentration of actual pitches. Separate standard quality indicators for the gasoline samples (with octane number 92), which are associated with the content of the components of petroleum fractions and other non-volatile compounds, were measured. The method of piezoquartz micro-weighting with one-sided loading of the resonant electrode of the resonator, sensitive on mass (OAB-type) with a limiting contour, is used. The correlation between the results obtained by piezoquartz micro-weighing and by the standard method was studied. Critical points of the developed method are determined - the stage of applying the exact volume of samples to the resonator electrode with a micro syringe. The method of molecular absorption spectroscopy in the middle UV region relative to hexane revealed differences in the composition of the components of the petroleum fraction of gasoline samples. The principle of comparing "fingerprints" is used to compare and establish the degree of identity of spectra and composition for gasoline samples from several characteristic points on the spectra. To find and evaluate the tightness of the connection between the results of different methods, a nonparametric method for small samples with the Spearman rank correlation was used. It is established that the values of the Spearman's correlation coefficients for the piezoquartz microweighting and the peak optical density present in all gasoline samples at the characteristic wavelength have a direct and strong tightness of the connection. The dependence of the signs is statistically significant, there is a close linear relationship between the parameters. The possibility of applying the piezoquartz micro-weighting method to develop an express method for estimating the non-volatile residue of gasoline was positively evaluated.