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

In the present paper, we use a gold electrode modified by a 2-(3, 4- dihydroxy phenyl) benzothiazole self-assembled monolayer (DHT-SAM) for 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 (alpha) 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 (alpha = 0:35), catalytic rate constant (k = 4:4 * 104M-1s-1) and diffusion coeffficient (D = 1:03*10-6 cm2s-1) were calculated for EP, using electrochemical approaches. Differential Pulse Voltammetry (DPV) exhibited a linear dynamic range over a 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 determination of EP in the EP ampoule.