Abstract

The reactivity of Diquat ion at the carbon paste electrode (C.P.E) modified by the copper (C.P.E-Cu) has been reported. The working electrode was prepared by mixing the copper with the carbon powder. The optimal potential window has been selected in the range from -1 V to 1.5 V. The effect of parameters such as pH, scan rate, preconcentration time and concentration has been studied by cyclic voltammetry. The preconcentration time is 13 minutes. The reactivity of Diquat on the electrochemical detector has been characterized by the appearance of the cathodic peak at 0.6 V in a solution of sodium sulfate (pH 3). Catalytic influence has been examined by cyclic voltammetry and electronic impedance spectroscopy. The calculated limits of detection and quantification have been 9.48·10^-6 and 3.16·10^-6 mol L^-1, respectively. Then relative standard deviation (RSD) at 0.8·10^-4 mol L^-1 of Diquat was 5.77 % for nine repetitions. The analytical application was done in the determination of Diquat in real samples of apple juice with satisfying results.

Keywords: N,N'-ethylene-2,2'-bipyridinium, cyclic voltammetry, electronic impedance spectroscopy, apple juice, electroanalysis, mixing, copper

Article language: En