A NEW ELECTROCHEMICAL ASSAY FOR THE DETERMINATION OF OH RADICAL SCAVENGER CAPACITY

The determination of OH radical scavenger capacity (ORSC) was performed using a new electrochemical sensor1 developed for the OH-radical detection that is based on the degradation of a polyphenol insulating film deposited on a glassy carbon electrode. In the presence of OH radicals the polyphenol film is attacked and that leaves the GC surface uncovered. The extent of degradation is estimated by cyclic voltammetry using the redox probe Ru(NH3)63+. In depencence on theantioxidant concentration, the time requested to induce the polymer degradation increases due to theprotective action of the compound (Figure 1). Such a time allows to estimate the ORSC. Five pure compounds, among the most common antioxidants, were classified as to their ORSC by generation of OH from H2O2 photolysis or Fenton reaction. The applicability of the electrochemical method was tested on eight real samples of fruit juices and the results compared to those obtained using traditional assays such as ORAC, ABTS and DPPH. ORAC was the methodology showing the best correlation with the developed electrochemical method, maybe since similar radical species are involved.