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

A novel efficient differential pulse voltammetric (DPV) method for determination gallic acid (GA) was developed by using an electrochemical sensor based on [Cu(2)tpmc](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 [Cu(2)tpmcGA](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 x 10(-7) to 1.0 x 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 x 10(-7) M, while at CGCE was 4.6 x 10(-6) M. CGE was successfully applied for the determination of the antioxidant capacity based on GA equivalents for white, rose and red wine samples. (C) 2014 Elsevier B.V. All rights reserved.