Electrochemical Determination of Flavonoid Fisetin in Commercial Dietary Supplements Using a Boron-Doped Diamond Electrode

摘要

For the first time, a boron-doped diamond electrode was utilized to quantitatively determine flavonoid fisetin (FST). Cyclic voltammetric studies have shown that the electrochemical oxidation of FST is irreversible and well-separated two peaks (P_(A1) and P_(A2)) in 0.1 MHNO3 solution. The effects of electrode pretreatment, solution pH, nature of the supporting electrolyte, and instrumental variables on the peak current and potentials of the FST were investigated by square-wave voltammetry (SWV) and then optimum ones were determined. It was observed that the cathodically pre-treated BDD (CPT- BDD) electrode's performance was better than the other pretreatment procedures for increasing the FST oxidation signal. Under optimized conditions and using the SWV technique, the response of the first anodic peak (P_(A1)) of the FST was proportional in a concentration range of 0.5-20.0 μg mL~(-1) (1.7×10~6-6.9×10~5 mol L~(-1)) with a detection limit of 0.08 μg mL~(-1) (2.8× 10~7mol L~(-1)). Also, it was successfully demonstrated that the proposed method is applicable in commercial nutritional supplement formulations.