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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