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.

A simple and efficient procedure is described for electrochemical determination of trifluoperazine (TFP), a prominent compound in a large group of phenothiazine derivatives with potent physiological activity. This method is based on the electrochemical oxidation of TFP in Britton–Robinson buffer solution in pH 6 at a boron-doped diamond electrode. Cyclic voltammetry provided a four well defined oxidation peaks at +0.65, +0.83, +1.06 and +1.35 V (vs. Ag/AgCl/3 M KCl electrode). Differential pulse voltammetry was applied as a very sensitive analytical technique for the determination of micromolar amounts of TFP. Two oxidation peaks on higher potentials were chosen for quantification of TFP. Under optimized conditions, the analytical curves obtained were linear in the TFP concentration range of 1.0 to 37.0 μmol L⁻¹, with a detection limit of 0.7 and 0.6 μmol L⁻¹, respectively. The effect of interfering agents (common urinary compounds) appeared to be negligible confirming the favourable selectivity of the method. The proposed method was analytically applied by determination of trifluoperazine content in model human urine samples with good accuracy (recoveries varied from 97% to 104%). The developed approach could be beneficial in analysis of TFP in biological samples using a boron-doped diamond electrode as an up-to-date electrochemical sensor and could represent an inexpensive analytical alternative to separation methods.