New molecular self-assembled monolayers on gold electrode for simultaneous determination of epinephrine and uric acid


Department of Chemistry, Faculty of Science, Yazd University, Yazd, I.R.Iran


In the present paper, we use a gold electrode modified by 2-(3, 4-dihydroxy phenyl) benzothiazole self-assembled monolayer (DHT-SAM) for the determination of epinephrine (EP) and uric acid (UA). Initially, DHT-SAM was characterized by different techniques. CV was used to investigate the redox properties of the modified electrode at various scan rates. The apparent charge transfer rate constant, ks and transfer coefficient (α) were calculated. Next, electro oxidation of epinephrine (EP) and uric acid (UA) on a gold electrode modified by a self-assembled monolayer of DHT mediated was investigated. At the optimum pH of 7.0, the oxidation of EP occurs at a potential about 200 mV less positive than that of an unmodified gold electrode. The values of transfer coefficients (α = 0.35), catalytic rate constant (k = 4.4 × 104 M-1s-1) and diffusion coefficient (D = 1.03 × 10-6cm2s-1) were calculated for EP, using electrochemical approaches. Differential pulse voltammetry (DPV) exhibited a linear dynamic range over the concentration range of 0.5–400.0 µM and a detection limit (3s) of 0.11 µM for EP in pH= 7. Finally, simultaneous determination of EP and UA at the modified electrode was described and used for the determination of EP in EP ampoule.