Differential Pulse Voltammetric Determination of Serotonin Using an Acid-Activated Multiwalled Carbon Nanotube – Over-Oxidized Poly(3,4-ethylenedioxythiophene) Modified Pencil Graphite Electrode

Abstract

In this study, acid-activated multi-walled carbon nanotubes (AA-MWCNT) and poly(3,4-ethylenedioxythiophene) (PEDOT) were deposited on a pencil graphite electrode (PGE) surface for electrochemical sensing applications. The acid-activated multi-walled carbon nanotube/over-oxidized poly(3,4-ethylenedioxythiophene) modified pencil graphite electrode (AA-MWCNT/OO-PEDOT/PGE) was characterized using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS). The sensing properties of the obtained surface were examined for the voltammetric determination of serotonin in a phosphate buffer solution. The effects of the pH, adsorption time, over-oxidation and polymerization parameters on the electrochemical properties of serotonin were investigated. The effects of possible interfering substances were evaluated. The detection limit was determined to be 0.092 µM based on a signal-to-noise ratio of 3. Analytical applications of AA-MWCNT/OO-PEDOT/PGE were successfully tested for the determination of serotonin in human blood serum samples.