Simultaneous Sensitive Determination of Dopamine and Uric Acid in the Presence of Excess Ascorbic Acid with a Magnetic Chitosan Microsphere/Thionine Modified Electrode

摘要

Magnetic chitosan microspheres (MCMS) and thionine were incorporated in a modified electrode for the simultaneous sensitive determination of dopamine (DA) and uric acid (UA). Due to the unique properties of the MCMS and the electron mediation of thionine, this modified electrode showed excellent electrocatalytic oxidation toward dopamine and uric acid with a large separation of peak potentials and a significant enhancement of peak currents. However, the electrochemical behavior of ascorbic acid may be depressed at the modified electrode. Differential pulse voltammetry was used for the simultaneous sensitive determination of dopamine and uric acid in the presence of excess ascorbic acid at this modified electrode. The current responses showed excellent linear relationships in the range of 2-30 μM and 9-100 μM for dopamine and uric acid, respectively. The detection limits were estimated to be 0.5 μM and 2.3 μM for dopamine and uric acid, respectively. In addition, this modified electrode showed excellent repeatability, good stability, and satisfactory reliability, thus indicating potential for the practical applications.