Amperometric detection of dopamine and ascorbic acid with zeolite-graphite composite microelectrodes

Abstract

Natural and synthetic zeolites were used to modify synthetic graphite based composite microelectrodes envisaging their use for simultaneous/selective detection of ascorbic acid (AA) and dopamine (DA) in aqueous solutions. Both natural and synthetic zeolite-modified synthetic graphite composite microelectrodes (ZN-GEC and SZ-GEC) were obtained in epoxy matrices, and the optimum composition was selected based on the electrochemical behavior. The composite electrodes were characterized electrochemically by cyclic voltammetry (CV) using the classical ferrycianide/ferrocyanide system method, in comparison with bare graphite composite microelectrode (GEC). The electrochemical oxidation of AA occurred at all three microelectrodes and the slowest kinetics was noticed for SZ-GEC, due to the synthetic zeolite presence with certain peculiarities in relation to the selectivity and the catalytic effect, while ZN-GEC and GEC microelectrodes exhibited very good sensitivity for AA detection in aqueous solution. Taking into consideration the fact that DA and AA coexist in real extracellular brain fluid and the fact that SZ-GEC microelectrode did not exhibited a good sensitivity towards AA detection, but a very good sensitivity for DA was obtained, makes this composite material a good candidate with real potential for selective determination of DA without a significant interference of AA. © 201 WIT Press.