Electrochemical non-enzymatic sensing of oxalic acid based on PdPt-modified electrodes: application to the analysis of vegetable samples

Abstract

The electrocatalytic properties of carbonaceous electrodes, electrochemically modified with microquantities of PdPt (low-platinum-content alloy), were evaluated with regards to electrooxidation of oxalic acid (OA). Electrochemical studies indicated that the electrodes possess high activity towards oxidation of OA, fast response, remarkable anti-interference performance, and high stability, defining them as promising cost-effective sensing materials for non-enzymatic detection of OA. At an applied potential of 0.75 V (vs. Ag/AgCl), modified glassy carbon PdPt/GC showed excellent analytical performance: sensitivity of 213.7 µA mM−1 cm−2, linear range 0.01–4.7 mM, detection limit of 1.0 µM, response time of 8 s, and good reproducibility (2.6% RSD, n = 10). The proposed electrode was successfully applied for amperometric determination of OA content in spinach and swiss chard samples. The simple and rapid procedure for electrode fabrication, technical simplicity, and demonstrated feasibility in food sample analysis, are great advantages of the developed electrochemical sensor.