Electrochemical Behaviour of a Modified Carbon Nanotube Paste Electrode and Its Application for Simultaneous Determination of Epinephrine, Uric Acid and Folic Acid

In this study, a carbon paste electrode modified with carbon nanotubes and 5-amino-3',4'-dimethylbiphenyl-2-ol (5ADB) was used to prepare a novel electrochemical sensor. The objective of this novel electrode modification was to seek new electrochemical performances for detection of epinephrine (EP) in the presence of uric acid (UA) and folic acid (FA). The peak potentials recorded in a phosphate buffer solution (PBS) of pH 7.0 were 270, 445 and 760 mV versus Ag/AgCl/KCl (3.0 M) for EP, UA and FA, respectively. Under the optimum pH of 7.0, the oxidation of EP occurs at a potential about 170 mV less positive than that of the unmodified CPE. The response of catalytic current with EP concentration shows a linear relation in the range from 1.2 x 10(-6) to 1.0 x 10(-3) M with a detection limit of 6.2 +/- 0.1 x 10(-7) M.