Simultaneous determination of dopamine and ascorbic acid on poly (3,4-ethylenedioxythiophene)modified glassy carbon electrode

摘要

Detection of dopamine (DA)in the presence of excess of ascorbic acid (AA)has been demonstrated using a conducting polymer matrix,poly (3,4-ethylenedioxythiophene)(PEDOT)film in neutral buffer (PBS 7.4)solution.The PEDOT film was deposited on a glassy carbon electrode by electropolymerization of EDOT from acetonitrile solution.Atomic force microscopy studies revealed that the electrodeposited film was found to be approximately 100 nm thick with a roughness factor of 2.6 nm.Voltammetric studies have shown catalytic oxidation of DA and AA on PEDOT modified electrode and can afford a peak potential separation of approx 0.2 V.It is speculated that the cationic PEDOT film interacts with the negatively charged ascorbate anion through favorable electrostatic interaction,which results in pre-concentration at a less anodic value.The positively charged DA tends to interact with the hydrophobic regions of PEDOT film through hydrophobic-hydrophobic interaction thus resulting in favorable adsorption on the polymer matrix.Further enhancement in sensitivity to micro molar level oxidation current for DA/AA oxidation was achieved by square wave voltammetry (SWV)which can detect DA at its low concentration of 1 uM in the presence of 1000 times higher concentration of AA (1 mM).Thus the PEDOT modified electrode exhibited a stable and sensitive response to DA in the presence of AA interference.