Electrocatalytic Determination of Dopamine in the Presence of Ascorbic Acid by Poly-L-proline and Ferricyanide Compound Film Modified Electrode

A novel biosensor was fabricated by the electrochemical polymerization of poly-L-proline（P-LP） and ferricyanide（FC） to form a compound film on a glassy carbon electrode（GCE）. The compound film modified electrode（P-LP/FC/GCE） shows electrocatalytic activity toward dopamine（DA） in a phosphate buffer solution（PBS, pH = 4.0） with a diminution of the overpotential and an increase in peak current. P-LP/FC/GCE was used to study the electrocatalytic oxidation of DA and ascorbic acid（AA） by means of cyclic voltammetry（CV）, differential pulse voltammetry（DPV） and amperometric i-t curve techniques. The overlapping anodic peaks of DA and AA were resolved into two well-defined voltammetric peaks in CV and DPV with the potential differences of about 200 and 225 mV, respectively. The peak current of DA is linearly change with the concentration of DA in a range of 1 × 10^-7 to 1.14 × 10^-4 mol/L with the correlation coefficient of 0.9997. The detection limit is 4.4~10-8 mol/L（S/N=3）. P-LP/FC/GCE exhibited an excellent selectivity, sensibility and stability for the determination of DA, and can be applied to the determination of dopamine injections with satisfied results.