Simultaneous determination of epinephrine and dopamineat with poly(L-arginine) modified electrode

A poly (L-arginine) chemical modified electrode (PLA/CME) was fabricated by electrochemical immobilization of L-arginine on a glassy carbon electrode (GCE) through cyclic voltammetry (CV). Simultaneous determination of dopamine (DA) and epinephrine (EP) has been studied at PLA/GCE. The PLA/GCE exhibited superior selectivity and sensitivity towards DA and EP in the presence of high concentrations of uric acid (UA) and ascorbic acid (AA). In pH 7. 5 phosphate buffer solution, the modified electrode gave a pair, of redox peaks at 0. 276 V and 0. 059 V for DA, three oxdition peaks and one cathodic peaks at 0. 262 V, 0. 121 V, -0. 126 V and -0. 316 V for EP, respectively. Two separated cathodic peaks was divided about 375 mV. The linear response were obtained in the range of 5. 0 x 10(-7) to 5. 0 x 10(-5) mol/L for EP, and 8. 0 x 10(-7) -5.0 x 10(-4) mol/L for DA. The detection limit were 1. 0 x 10(-7) mol/L for EP and 3. 0 x 10(-7) mol/L for DA. The method was successfully applied to the simultaneous determination of DA and EP in human urine samples. Electrochemical behavior of DA and EP on the PLA/GCE were also investigated.