Electrochemical Determination of Diclofenac Sodium in Aqueous Solution on Cu-Doped Zeolite-Expanded Graphite-Epoxy Electrode

The electrochemical oxidation and determination of diclofenac sodium (DCF) at Cu-doped zeolite-modified expanded graphite-epoxy composite (CuZEGE) electrode was evaluated for a new alternative of quantitative determination of sodium diclofenac in aqueous solutions. Cyclic voltammetry was used to characterize the electrochemical behaviour of the electrode in the presence of diclofenac sodium in a 0.1 M NaOH supporting electrolyte. This modified electrode exhibited electrocatalytic effect towards sodium diclofenac oxidation, allowing its determination in aqueous solution. The linear dependence of the current versus diclofenac concentration was obtained using cyclic voltammetry, chronoamperometry, differential-pulsed voltammetry. The limit of detection for DCF reached by direct analysis on CuZEGE is from 2 x 10(-5) to 3 x 10(-7) M in relation with used technique and the potential value. Substantial enhancement of the electroanalytical parameters, e.g. the limit of detection of 5 x 10(-8) M. for the determination of DCF at CuZEGE electrode was reached by applying a chemical preconcentration step prior to voltammetric quantification.