Sayed Mehdi Ghoreishi - Department of Analytical Chemistry, Faculty of Chemistry, University of Kashan, Kashan, I.R. Iran.
Asma Khoobi - Department of Analytical Chemistry, Faculty of Chemistry, University of Kashan, Kashan, I.R. Iran.
Fahimeh Zeraatkar Kashani - Department of Analytical Chemistry, Faculty of Chemistry, University of Kashan, Kashan, I.R. Iran.

4-Hydroxybenzoic acid is primarily known as the basis for the preparation of its esters, known as parabens, are widely used as bactericides and preservative agents in cosmetic, pharmaceuticaland personal care products, as well as in processed food and beverages, for inhibiting the development of microorganisms and therefore prolonging products’ shelflife [1]. But human exposure to p-hydroxybenzoic acid esters is a concern, owing to adverse healtheffects of these compounds [2]. In the present work, the electrochemical oxidation of 4-Hydroxybenzoic acid has been studied using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques at the surface of a nickel nanoparticles modified carbon paste electrode. The characterization of themodified electrode was studied using different methods such as scanning electron microscopy(SEM), electrochemical impedance spectroscopy (EIS) and CV. Also for electrochemical studies of paraben various electrochemical techniques such as chronoamperometry, chronocoulometryand linear sweep voltammetry (LSV) were applied. The modified electrode exhibited excellentelectrocatalytic activity towards the oxidation of paraben. After optimizing the experimental conditions, the anodic peak current of paraben showed a linear correlation to its concentration ina broad linear dynamic range (0.7-1000.0 μM) with low limit of detection (62.0 ηM). Also the modified electrode presented a good stability and repeatability toward the determination of paraben. The results indicated that the nanostructured modified electrode could be employed for the determination of paraben in real samples with satisfactory results.

4-Hydroxybenzoic acid, Parabens, Nickel nanoparticles, Carbon paste electrode,electrochemical studies