Antioxidant capacity measurement of aniline-pyrrole copolymer by FRAP assay

Abstract

Based on wide variety of methods in evaluation of antioxidant activity, Ferric Reducing Antioxidant Power (FRAP) assay is another simple test to assess the total antioxidant power of aniline-pyrrole copolymer poly[Ani-co-Py] in this study. Initially, the electrosynthesis of poly[Ani-co-Py] was done by cyclic voltammetry (CV) method in acidic medium (H3PO4) containing different molar fraction of calcium chloride (CaCl2) and paratoluene sulfonic acid (PTSA). After characterization and structural analysis of modified electrodes by SEM, FTIR and UV-vis spectroscopy, the antioxidant activity was proven. In the study of antioxidant power, the operation of FRAP assay at low pH depends on the reduction of ferric tripyridyltriazine [Fe3+-TPTZ] complex to the intensely blue colored ferrous tripyridyltriazine [Fe2+-TPTZ] by antioxidants. This reduction is monitored by measuring the change in absorption maximum at 593 nm. Ultimately, the obvious changes in both color and absorption development at 593 nm confirmed the antioxidant capability of aniline-pyrrole electrocopolymerized electrodes.