The determination of oxidation degree (as peroxides formation) was performed according to the ferricthiocyanate method: 30 μL of the reaction mixture was added to 2.91 ml of 75% ethanol, 30 μL of 30% ammonium thiocyanate and 30 μL of 0.02 M ferrous chloride in 3.5% hydrochloric acid. Mixtures were shaken and exactly after 3 min the absorbance was measured at 500 nm [9].