Fast Determination of Antioxidant Capacity of Food Samples Using Continuous Amperometric Detection on Polyester Screen‐printed Graphitic Electrodes

The determination of antioxidant capacity of food samples using disposable polyester screen‐printed graphitic macroelectrodes (SPGE) coupled with a batch‐injection cell based on the measurement of the consumption of 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH.) is reported. The SPGEs are organic‐resistant electrodes and thus compatible with food samples and organic solvents used to dissolve DPPH.. A micropipette controlled the release (193 μL s−1) of sample (150 μL) upon the sensor/working electrode immersed in electrolyte (1 : 1 ethanol/methanol containing 0.05 mol L−1 LiCl). The first demonstration of this protocol was devoted to the analysis of edible oils. The remaining DPPH. was amperometrically detected at +0.1 V (vs. pseudo AgCl). The antioxidant capacity (percentage of DPPH. scavenging and mg equivalent of tocopherol) was obtained using the proposed and spectrophotometric methods. The results were in agreement according to t‐test (confidence level of 95 %). The method is precise (RSD=2.3 %, n=12), fast (180 h−1), presents low detection limit of DPPH. (1 μmol L−1), and allows on‐site analysis. Moreover, the proposed method can be extended to the analysis of antioxidant capacity of other samples of agricultural and food interests.