Determination of Antioxidant Capacity and Total Phenolic and Ascorbic Acid Contents of Some Fruits and Vegetables with an Electrochemical Approach

Abstract

Abstract The determination of antioxidant capacity, total phenolic and ascorbic acid contents with high accuracy and efficiency, low cost, and fast methods has great analytical importance. The antioxidant capacity, total phenolic and ascorbic acid contents of apricot, arugula, banana, cranberry, spinach, and strawberry were investigated with an electrochemical approach and their compatibility with conventional methods. Antioxidant activity was determined by ABTS and DPPH assays, total phenolic content was determined by the Folin Ciocalteu method, which are spectrophotometric techniques, and ascorbic acid was quantified by HPLC technique. In order to perform more sensitive and simultaneous measurements in electrochemical measurements, the surface of the glassy carbon electrode was modified by electropolymerization of p-toluene sulfonic acid (TSA/GCE). The TSA/GCE modified sensor was used for the first time for the determination of antioxidant capacity and total phenolic content. The surface of the modified sensor was characterized by cyclic voltammetry and scanning electron microscopy. The TSA/GCE sensor was linearly correlated with the DPV technique for Trolox and gallic acid in 0.1 M NaNO3 and ascorbic acid in phosphate buffer solution pH 7.4 supporting electrolyte solution. Electrochemical methods have offered a promising alternative for the determination of antioxidant capacity and total phenolic content due to their simplicity, rapid response, low cost, sensitivity, and reproducibility.