Development of an Electrochemical Cupric Reducing Antioxidant Capacity Method (CUPRAC) for Antioxidant Analysis

Cupric Reducing Antioxidant Capacity method, CUPRAC, is a reliable assay for determining Total Antioxidant Capacity (TAC) in samples of foods, beverages and pharmaceutical formulations. In this work, an electrochemical approach was used to quantify antioxidant content employing a variation of the CUPRAC assay, as the concentrations of the participating species ([Cu(Nc)2]2+ and [Cu(Nc)2]+) can be evaluated by electrochemical measurements. Then, monitoring the voltammetric peak and chronoamperometric diffusional current, it was possible to quantify the content of antioxidants, with high analytical performance. Statistical analysis allowed establishing parameters like linearity, detection and quantification limits, recovery, precision and trueness. These validation parameters demonstrate that electrochemical CUPRAC methods are comparable with the classical spectrophotometric method. Electrochemical CUPRAC was employed to determine antioxidant content in tea samples and the results showed that the content of flavonoids determined the required time for complete antioxidant consumption.