In Ukrainian

Abstract

The purpose of this work was to determine the patterns of quercetin and rutin sorption on the aluminium oxide as dependent on concentration and pH of their water-ethanol solutions to develop the assays of the sorption-spectrophotometric determination of these natural flavonoids in preparations of plant origin. Complex adsorption and spectral studies of the interaction of quercetin and rutine with pyrogenic aluminium oxide in a water-ethanolic medium have been carried out. The flavonoid sorption on aluminium oxide starts at pH > 2.5 and reaches the maximum values in a neutral medium, correlating with the content of non-dissociated surface ≡AlOH groups. Both quercetin and rutin sorption is described with the H-type isotherms which is typical for the chemisorption. The found coincidence of spectral characteristics of flavonoids on the aluminium oxide surface and in solutions containing Al(III) ions indicates the formation of similar chelate complexes in these systems. The spectral characteristics (intensity and position of the absorption bands) of flavonoids adsorbed on the surface of aluminium oxide depend on their concentration and pH of aqueous solutions. The intensity of sorbent colour is proportional to the surface concentration of quercetin and rutin and values of their conditional molar absorption coefficients in 0.025 % alumina dispersion were determined (e S 434 = 4386 g/mol∙cm and e S 403 = 5280 g/mol∙cm respectively). In addition, the absorbance of such dispersions linearly depends on the flavonoid concentration in analyzed solutions. Thus, aluminium oxide is found to be a promising solid-phase reagent for the determination of quercetin and rutin in preparations of medicinal plants by spectrophotometric or visual test methods.