▎ 摘　　要

Dopamine (DA) is an important neurotransmitter that belongs to the catecholamine group and plays a very significant role in the central nervous, renal, hormonal, and cardiovascular systems. As a result, dysfunction of the dopaminergic system in the central nervous system (CNS) has been related to neurological disorders such as schizophrenia and Parkinson's disease. Therefore, in this work, a screen-printed electrode was modified by graphene quantum dots (GQD/SPE) in order to be used as sensor for dopamine in the presence of tyrosine. To evaluate the efficiency of the developed electrode toward detection of dopamine and tyrosine in aqueous solutions, various electrochemical methods including cyclic voltammetry (CV), chronoamperometry (CHA), and differential pulse voltammetry (DPV) techniques were employed. Application of GQD/SPE created a separation of 435mV in the oxidation peak potentials of dopamine and tyrosine. The calibration curves were within the range of 0.1-1000.0 and 1.0-900.0M for dopamine and tyrosine, respectively. The detection limits (S/N=3) were determined as 0.05 and 0.5M for dopamine and tyrosine, respectively. The diffusion coefficients using chronoamperometry at the surface of modified electrode were determined as 9.0x10(-5) and 6.4x10(-5)cm(2)s(-1) for dopamine and tyrosine, respectively.