Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
6604114 | Electrochimica Acta | 2018 | 50 Pages |
Abstract
Here we present a sensitive and selective electrochemical sensor that has been developed for the analysis of uric acid and ascorbic acid in milk with minimum interference from each other. A conducting polymer, poly(3,4-ethylenedioxythiophene) (PEDOT), was prepared electrochemically as a thin layer on a glassy carbon electrode and then acclimatized to an aqueous buffer before sample analysis. The modified sensor showed an excellent catalytic response towards the oxidation of uric acid, with an anodic peak during cyclic voltammograms at around 350â¯mV (Ag/AgCl), taken at pH 6.6 as typical of untreated milk samples. A small peak due to ascorbic acid was located close to 0â¯mV, enabling the simultaneous detection of the two antioxidants. A stronger response for ascorbic acid was produced at pH 3, a pH value obtained after treating milk with acids to remove protein material prior to HPLC analysis. The electrochemical oxidation of uric acid at the modified electrode involved pre-adsorption of uric acid and a form of stripping voltammetry. This was not the case with ascorbic acid where the oxidation proceeded under diffusion control, with a diffusion coefficient of 6.9â¯Ãâ¯10â6â¯cm2â¯sâ1 obtained from cyclic voltammograms. Good linear relationships between peak current intensities and concentrations were obtained in the range of 6-100â¯Î¼M for uric acid and 30-500â¯Î¼M for ascorbic acid. The sensitivity and limit of detection (S/Nâ¯=â¯3) for the PEDOT-modified electrode were 2.5â¯Î¼Aâ¯Î¼Mâ1â¯cmâ2 and 7â¯Î¼M for uric acid, and 0.6â¯Î¼Aâ¯Î¼Mâ1â¯cmâ2 and 45â¯Î¼M for ascorbic acid, respectively. The newly developed sensor was successfully applied to milk samples for a fast voltammetric determination of uric acid and ascorbic acid concentration.
Keywords
Related Topics
Physical Sciences and Engineering
Chemical Engineering
Chemical Engineering (General)
Authors
Mahsa Motshakeri, Jadranka Travas-Sejdic, Anthony R.J. Phillips, Paul A. Kilmartin,