A Selective Voltammetric Method for Detecting Dopamine at Quercetin Modified Electrode Incorporating Graphene

The development of a quercetin-graphene composite-modified glassy carbon electrode (Qu/GH/GCE) for the selective and sensitive detection of dopamine (DA) is described in this paper. To fabricate the Qu/GH/GCE, graphene (GH) was first coated onto the surface of a glassy carbon electrode (GCE) and then quercetin (Qu) was electrodeposited on the OH matrix. Transmission electron microscopy (TEM) was used to characterize the morphology of the obtained GH and Qu/GH, and the electrochemical properties of the modified electrode were studied using electrochemical techniques. The as-prepared Qu/GH/GCE occupied a synthetic property between GH and Qu. The common overlapped electrochemical oxidation peaks of DA and AA were completely separated and a remarkable increasing electron-oxidation current of DA occurred on the Qu/GH/GCE, which enabled the sensitive and selective electrochemical detection of DA in the presence of ascorbic acid (AA) with peak difference of ca. 452 mV between DA and AA. The peak current obtained at 0.174 V (vs. saturated calomel electrode, SCE) from differential pulse voltammetry (DPV) is linearly dependent on the DA concentration in the range from 3.0x10(-8) to 4.0x10(-4) mol/L with a detection limit of 1.0x10(-8) mol/L. Furthermore, the Qu/GH/GCE exhibits good reproducibility and stability, and has been used for the determination of DA in samples of rat's striatum tissue with satisfactory results.