A new method for electrocatalytic oxidation of ascorbic acid at the Cu(II) zeolite-modifled electrode

Anew method is developed for the catalytic oxidation or ascorbic acid at graphite zeolite-modified electrode, doped with copper(II) (Cu(2+)A/ZCME). Copper(II) exchanged in zeolite type A acts as catalyst to oxidize ascorbic acid. The modified electrode lowered the overpotential of the reaction by similar to 400mV. First. the electrochemical behavior of copper(II), incorporated in the zeolite type A modified electrode, was studied. The results illustrate that diffusion can control the copper(II)lcopper(0) redox process at the Cu(2+)A/ZCME. Then, the behavior or electrocatalytic oxidation reaction for ascorbic acid was researched. The electrode was employed to study electrocatalytic oxidation of ascorbic acid, using cyclic voltammetry and chronoamperometry as diagnostic techniques. The diffusion coefficient of ascorbic acid was equal to 1.028 x 10(-5) cm(2) s(-1). A linear calibration graph was obtained over the ascorbic acid with a concentration range of 0.003-6.00 mmol L-1. The detection limit (DL) of ascorbic acid was estimated as 2.76 x 10(-7) mol L-1.The relative standard deviations of 10 replicate measurements (performed on a single electrode at several ascorbic acid concentrations between 3.0 and 200 mu mol L-1) were measured between 1.0 and 2.4%. (C) 2008 Elsevier B.V. All rights reserved.