Simultaneous determination of ascorbic acid, epinephrine and uric acid at over-oxidized poly(p-aminophenol) film modified electrode

A modified electrode was fabricated by over-oxidation of polymer film after electropolymerization of p-aminophenol on a bare glassy carbon surface. A higher catalytic activity was obtained for electrocatalytic oxidation of ascorbic acid (AA), epinephrine (EN), and uric acid (UA) in pH 7.4 phosphate buffer solution (PBS) at over oxidized poly(p-aminophenol) film modified glassy carbon electrode (Ox-PAP/GCE) due to an enhanced peak current and well-defined peak separations compared with both bare glassy carbon electrode (GCE) and poly(p-aminophenol) film modified GCE (PAP/GCE). The electrode surfaces were characterized by scanning electron microscopy (SEM) and Atomic Force Microscopy (AFM). Individual and simultaneous determination of AA, EN, and UA were carried out by differential pulse voltammetry. The detection limits were individually calculated for ascorbic acid, epinephrine, and uric acid as being 1.0 × 10−6 M, 6.5 × 10−9 M, and 1.8 × 10−7 M, respectively.

Cyclic voltammograms of AA (5 × 10−4 M), EN (1 × 10−4 M) and UA (1 × 10−4 M) at bare GCE, PAP/GCE and Ox-PAP/GCE. Inset shows the cyclic voltammetric behavior of all electrodes in pH 7.4 PBS in the absence of AA, EN and UA.Figure optionsDownload as PowerPoint slideHighlights
► Simultaneous determination of AA, EN, and UA was carried out by DPV.
► The electrode surfaces were characterized by SEM and AFM.
► The detection limits of EN were calculated as 6.5 × 10−9 M.
► Ox-PAP/GCE was used for analysis of real samples.