Electrochemical determination of uric acid at ordered mesoporous carbon functionalized with ferrocenecarboxylic acid-modified electrode

Ordered mesoporous carbon (OMC) functionalized with ferrocenecarboxylic acid (Fc) was used to modify the glassy carbon (GC) electrode. The characterization of OMC-Fc shows that, after anchoring ferrocene on the mesoporous, ordered mesostructure of the material (OMC-Fc) remains intact and Fc is electrochemically accessible. The obtained OMC-Fc-modified electrode was used to investigate the electrochemical behavior of uric acid (UA). UA oxidation is catalyzed by this electrode in aqueous buffer solution (pH 7.3) with a decrease of 200 mV in overpotential compared to GC electrode. The detection and determination of UA in the presence of ascorbic acid (AA), the main interferent, were achieved. The voltammetric signals due to UA and AA were well separated with a potential difference of 308 mV, a separation that can allow the simultaneous determination of UA and AA. With amperometric method, at a constant potential of 375 mV, the catalytic current of UA versus its concentration shows a good linearity in the range 60-390 mu M (R = 0.998) with a detection limit of 1.8 mu M (S/N = 3). These results are not influenced by the presence of AA in the sample solution. With good stability and reproducibility, the present OMC-Fc-modified electrode was applied in the determination of UA content in urine sample and satisfactory results were obtained. (c) 2008 Elsevier B.V. All rights reserved.