Simultaneous determination of uric acid and ascorbic acid at a ferrocenium-thioglycollate modified electrode.

Abstract

Self-assembled monolayers (SAMS) of chemisorbed thioglycollate on a gold electrode surface have been used as a base interface for the electrostatic adsorption of ferrocenium ion. Electrochemical impedance spectra (EIS) and cyclic voltammetry (CV) were used to evaluate the electrochemical properties of the supramolecular film. The bare gold electrode failed to distinguish the oxidation peaks of ascorbic acid (AA) and uric acid (UA) in phosphate buffer solution (PBS, pH 7.0), while the ferrocenium-thioglycollate modified electrode could separate them efficiently. In differential pulse voltammetric measurements, the prepared gold electrode could separate AA and UA signals, allowing the simultaneous determination of AA and UA. Under optimal conditions and within the linear range of 1.0 x 10(-6) to 5.0 x 10(-4) M, the detection limits of AA and UA achieved were 2.0 x 10(-7) and 1.0 x 10(-7) M, respectively. The applicability of the prepared electrode was demonstrated by measuring AA and UA in human urine without any pretreatment.