REVUE ROUMAINE DE CHIMIE, vol.65, no.4, pp.375-385, 2020 (SCI-Expanded)
The chemical structures of quercetin and luteolin are quite similar; as a result, their oxidation peaks potential are close and interfere each other. To solve this problem, in this study, the simultaneous determination method of quercetin and luteolin has been developed on glassy carbon electrode (GCE) by using differential pulse voltammetry (DPV). 75% methanol (hydro-alcoholic) support electrolyte was used for this purpose. The peak potential difference between the quercetin and luteolin was at about 110 mV which was useful for the simultaneous electrochemical analysis of both species. The experimental parameters were optimized. Under optimized conditions, linearity was obtained in the ranges of 0.079 - 39.60 x 10(-7) M and 39.60 - 148.50 x 10(-7) M for quercetin, and 0.065 - 32.60 x 10(-7) M and 32.60 - 122.50 x 10(-7) for luteolin. The detection limits for quercetin and luteolin were 0.022 x 10(-7) M and 0.018 x 10(-7) M, respectively. Finally, the present method was employed for the simultaneous determination of quercetin and luteolin in the ethanol and methanol extracts of Mate and White tea samples, and the obtained results were verified by high performance liquid chromatography as a confirmatory method.