L-Cysteine/Graphene oxide for electrochemical determination of ascorbic acid in the presence of dopamine and uric acid

Abstract

Ascorbic acid (AA), also known as vitamin C, has many roles in biological systems, such as prevention of cancer and common cold. Determination of AA is essential for food and pharmaceutical industries. Nowadays, electrochemical method is a potential method for detecting AA. However, detection of AA in presence of biological compounds, e.g. dopamine (DA) and uric acid (UA), is big challenge because these compounds are commonly found in biological samples and interfere the oxidation peak potential of AA. To overcome this problem, electrochemical coating of cysteine on graphene oxide decorated screen-printed electrode (Cys/GO/SP) was newly used for determination of AA. Field emission scanning electron microscope, energy dispersive x-ray and EIS were used to characterize the composites. AA of different concentrations were determined in phosphate buffer saline that has 10-µM DA and 10-µM UA using by differential pulse voltammetry (DPV). Cys/GO/SP presented three oxidation peaks corresponding to AA, DA and UA, whereas GO/SP and SP provided single peak. The oxidation peak currents of AA showed good linear relationship with AA concentrations of 0.5 - 5 mM with the detection limit of 0.26 mM. The results suggest that Cys/GO/SP can be used for electrochemical determination of AA in the interference of DA and UA.