International Journal of Electrochemical Science (Jan 2008)
Voltammetric Behavior and Amperometric Determination of Ascorbic Acid at Cadmium Pentacyanonitrosylferrate Film Modified GC Electrode
Abstract
The present work, describes electrochemical preparation of a novel cadmium pentacyanonitrosylferrate (CdPCNF) film as a Prussian Blue analogous on the glassy carbon (GC) electrode from a solution of 5 mM CdCl2 and 5 mM Na2[Fe(CN)5NO]. The effect of experimental conditions such as pH and composition of electrodeposition solution on the peak current of the modified electrode and its stability were investigated. In the optimized conditions a controllable and repeatable value of CdPCNF film was obtained. The modified GC electrode showed a reversible cyclic voltammograms due to the redox reaction of Fe(III) / Fe(II) in the film. The CdPCNF film showed a good electrocatalytic activity toward the oxidation of ascorbic acid. The mean value of rate constant k and the diffusion coefficient of ascorbic acid in the solution D, were found to be 3.6 ´ 102 M-1 s-1, and 4.4 ´ 10-6 cm2 s-1 respectively. A calibration graph was obtained over concentration of 5 – 50 µM. The limit of detection was found to be 2.52 µM by hydrodynamic amperometry. This technique was used to the selective determination of ascorbic acid in the pharmaceutical preparations and fruit juices.
