Dinuclear copper(II) octaazamacrocyclic complex in a PVC coated GCE and graphite as a voltammetric sensor for determination of gallic acid and antioxidant capacity of wine samples

•Synthesized copper/macrocyclic complex is sensitive to detect gallic acid.•Voltammetric sensor based on copper/macrocyclic complex is developed.•The lower detection limit is recorded at modified graphite then glassy carbon electrode.•Sensor was applied for the determination of the antioxidative capacity of wine samples.•Copper macrocyclic complex is explored by molecular modeling and DFT calculations.

A novel efficient differential pulse voltammetric (DPV) method for determination gallic acid (GA) was developed by using an electrochemical sensor based on [Cu2tpmc](ClO4)4 immobilized in PVC matrix and coated on graphite (CGE) or classy carbon rod (CGCE). The proposed method is based on the gallic acid oxidation process at formed [Cu2tpmcGA]3+ complex at the electrode surface. The complexation was explored by molecular modeling and DFT calculations. Voltammograms for both sensors, recorded in a HNO3 as a supporting electrolyte at pH 2 and measured in 2.5×10−7 to 1.0×10−4 M of GA, resulted with two linear calibration curves (for higher and lower GA concentration range). The detection limit at CGE was 1.48×10−7 M, while at CGCE was 4.6×10−6 M. CGE was successfully applied for the determination of the antioxidant capacity based on GA equivalents for white, rosé and red wine samples.

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