INFIQC   05475
INSTITUTO DE INVESTIGACIONES EN FISICO- QUIMICA DE CORDOBA
Unidad Ejecutora - UE
artículos
Título:
Highly sensitive determination of uric acid in the presence of ascorbic acid at glassy carbon electrodes modified with carbon nanotubes dispersed in polylysine
Autor/es:
MARCELA C. RODRíGUEZ, JOSé SANDOVAL, LAURA GALICIA, SILVIA GUTIéRREZ, GUSTAVO A. RIVAS*
Revista:
Sensors and Actuators B
Referencias:
Año: 2008
Resumen:
This article reports the highly selective and sensitive uric acid quantification in the presence of ascorbic acid using glassy carbon electrodes (GCE) modified with multi-wall carbon nanotubes (MWCNT) dispersed in polylysine (Plys) (GCE/MWCNT-Plys). The electrocatalytic activity of MWCNT deposited on glassy carbon electrodes has allowed an important decrease in the overvoltages for ascorbic acid oxidation (440 mV), making possible the clear definition of the oxidation processes of ascorbic acid and uric acid. Two protocols for uric acid quantification are described, the direct Differential Pulse Voltammetry (DPV) detection, and the DPV-Adsorptive Stripping detection with medium exchange. For the direct determination of uric acid, the sensitivities were (9.8 ± 0.2) x 104 ìAM-1 (r2= 0.994), and (10.7 ± 0.2) x 104 ìAM-1 (r2= 0.994) in the presence and absence of 1.0 mM ascorbic acid, respectively. The detection limit for uric acid in the mixture was 17 ìM. In the case of DPV-Adsorptive-Stripping determination, an important enhancement in sensitivity was obtained, allowing the detection of 2.2 ìM uric acid in a mixture containing 1.0 mM ascorbic acid. The sensor was successfully used for the quantification of uric acid in serum samples. 4 ìAM-1 (r2= 0.994), and (10.7 ± 0.2) x 104 ìAM-1 (r2= 0.994) in the presence and absence of 1.0 mM ascorbic acid, respectively. The detection limit for uric acid in the mixture was 17 ìM. In the case of DPV-Adsorptive-Stripping determination, an important enhancement in sensitivity was obtained, allowing the detection of 2.2 ìM uric acid in a mixture containing 1.0 mM ascorbic acid. The sensor was successfully used for the quantification of uric acid in serum samples.