Simultaneous Determination of Epinephrine and Dopamine with Poly(L-arginine) Modified Electrode

A poly(L-arginine) chemical modified electrode (PLA/GCE) 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 carried out using PLA/GCE. The PLA/GCE exhibited superior selectivity and sensitivity toward DA and EP in the presence of high concentrations of uric acid (UA) and ascorbic acid (AA). When the modified electrode was placed in phosphate buffer solution of pH 7.5, it gave a pair of redox peaks at 0.276 V and 0.059 V for DA, and three anodic peaks and one cathodic peak at 0.262 V, 0.121 V, −0.126 V and −0.316 V for EP, respectively. The two cathodic peaks were separated by a potential difference of 375 mV. The linear responses were obtained in the range of 5.0 × 10−7−5.0 × 10−5 M for EP, and 8.0 × 10−7−5.0 × 10−4 M for DA. The detection limits were 1.0 × 10−7 M for EP and 3.0 × 10−7 M for DA. The method was successfully applied for the simultaneous determination of DA and EP in human urine samples. Electrochemical behavior of DA and EP on the PLA/GCE was also investigated.