Cyclic Voltammetric Determination of N, N’-ethylene-2,2’Bipyridinium Concentration using Natural Phosphate Modified Carbon Paste Electrode

A carbon paste electrode (CPE) modified by natural phosphate (NP) has been evaluated using the electrochemical detector in the analysis of N, N’-ethylene-2,2’bipyridinium (DQ). The working electrode was obtained by depositing the NP on the surface of the CPE. The optimal potential window from -1.2 V to 1.6 V has been selected. DQ has been pre-concentrated on the surface of the CPE-NP in 0.1 M K2SO4 (pH 3). The reactivity of DQ on the electroanalysis detector was characterized by the appearance of the anodic peak at 0.7 V and the cathodic peak at 0.25 V. The influence of parameters such as pH, scan rate, accumulation time and concentration were studied by cyclic voltammetry. The optimal preconcentration time is 16 min. The kinetics of electron transfer on the CPE-NP in the detection of analyte was found using the scan rate effect. The concentration variation was studied. The scan rate effect has been showed the electrode process is adsorption controlled. The redox peak currents indicated a linear dependence with the DQ concentrations (1×10-5mol.L-1 - 6×10-5 mol.L-1). The results have been showed that the CPE-NP exhibited an excellent electro-catalytic activity for the DQ analysis. The calculated limits of detection and quantification have been 9.24×10-8 and 3.08×10-7 mol.L-1, respectively. The present electrochemical detector shows excellent performance in detecting the DQ. The proposed method has been applied to the determination of DQ concentration in a real sample of river water with satisfying results.