Electrochemical characterization of rutin in different electrolytes

The aim of this study was to examine electrochemical properties of rutin (a flavonoid widely distributed in fruits and vegetables, e.g. apples, buckwheat, green tea, aronia berries etc.) in three different electrolytes (KCl, NaCl, LiCl) by cyclic and differential pulse voltammetry (Ic = 0.34 mol dm-3). Measurements were conducted in a three electrode voltammetric cell in an aqueous media. Glassy carbon was used as a working electrode, platinum wire as counter electrode and Ag/AgCl electrode as a reference electrode. Inert atmosphere was acomplished by system purging with high purity argon Ar 5 (Ar = 99.999 %), before each measurement. Cyclic voltammograms of rutin revealed two oxidation peaks in all three electrolytes, which were associated with oxidation of four - OH groups of quercetin. The first oxidation peak was reversible and it corresponds to the oxidation of the 3`, 4`- dihydroxy groups on the B-ring of rutin and the second oxidation peak was irreversible and it corresponds to oxidation of 5, 7-dihydroxy groups on the A-ring of rutin. Differential pulse voltammograms also revealed two oxidation peaks. Linear dependence of Ip vs. rutin concentration was found in all three electrolytes. The best calibration diagram was obtained in 0.34 mol dm-3 KCl solution in rutin concentration range from 1.0∙10-6 mol dm-3 to 4.2∙10-5 mol dm-3