Voltammetric Determination of Dopamine in Human Serum with Amphiphilic Chitosan Modified Glassy Carbon Electrode

An improvement of selectivity for electrochemical detection of dopamine (DA) with differential pulse voltammetry is achieved by covalently modifying a glassy carbon electrode (GCE) with O-carboxymethylchitosan (OCMCS). The amphiphilic chitosan provides electrostatic accumulation of DA onto the electrode surface. In a phosphate buffer solution (pH 6.0), a pair of well-defined reversible redox waves of DA was observed at the OCMCS/GCE with a ΔE(p) of 52 mV. The anodic peak current obtained from the differential pulse voltammetry of dopamine was linearly dependent on its concentration in the range of 6.0 × 10(-8) to 7.0 × 10(-6) M, with a correlation coefficient of 0.998. The detection limit (S/N = 3) was found to be 1.5 × 10(-9) M. The modified electrode had been applied to the determination of DA in human serum samples with satisfactory results.