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 Delta E-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 x 10(-8) to 7.0 x 10(-6) M, with a correlation coefficient of 0.998. The detection limit ( S/N = 3) was found to be 1.5 x 10(-9) M. The modified electrode had been applied to the determination of DA in human serum samples with satisfactory results.