Determination of Epinephrine at a Screen-Printed Composite Electrode Based onGraphite and Polyurethane

A screen-printed electrode based on a graphite and polyurethane composite (SPGPU) was used in the determination of epinephrine (EP) in cerebral synthetic fluid (CSF) sample. Both Differential Pulse Voltammetry (DPV) and Square Wave Voltammetry (SWV) were used to investigate the suitability of sensor for determination of EP. Under the optimum conditions, the analyte oxidation signal was observed at 0.17 and 0.080 V for DPV and SWV, respectively (vs. pseudo-Ag¦AgCl) in phosphate buffer (pH=7.4). A linear region between 0.10 and 1.0 µmol L-1 was observed in DPV, with detection limit of 6.2 × 10-7 mol L-1 (R=0.997). In SWV two linear ranges were observed, the first one between 0.10 and 0.80 µmol L-1 and the second from 1.0 to 8.0 µmol L-1 with limit of detection 9.5 × 10-8 and 6.0 × 10-7 mol L-1 (R=0.998) respectively. Recoveries of 99 to 100% were observed using the sensor for determination of epinephrine in the CSF. Interference tests showed that uric and ascorbic acids as well as dopamine increase the current of epinephrine, with acceptable levels for UA. The use of a standard addition of EP in the CSF solution containing the ascorbic acid allowed minimizing such interference.