Development of voltammetric methods for antioxidant activity determination based on Fe(III) reduction

Abstract Numerous methods have been developed for determination of antioxidant (AO) activity in vitro, but only several spectrophotometrical assays are frequently applied. Among them, probably the most simple is FRAP assay, based on the reduction of Fe(III) to Fe(II) by antioxidants. In this work the applicability of that reaction for the development of electrochemical method for AO activity determination was examined. The two common electrochemical techniques: direct current polarography and cyclic voltammetry on platinum working electrode were used. The developed fast, simple and without a need for the calibration against standard (such as Trolox or gallic acid) electrochemical methods were applied to determination of the AO activity of ten natural antioxidants. The AO activities determined by two developed methods and three frequently applied spectrophotometric assays (ABTS, DPPH and FRAP) correlated well. All the obtained correlation coefficients (R) were above 0.9. The cyclic voltammetric method fulfills green chemistry principles.