Ascorbic Acid, L-lysine, L-tyrosine Single Molecular Layer Of Glassy Carbon Modified Electrode In The Detection Of Dopamine

Chemically modified electrodes are prepared by designing the electrode surfaces on the molecule level, and have shown splendid prospects in sensitivity and selectivity, which have been used in various fields in the electroanalysis chemistry.This paper constructed amino monolayer glassy carbon modified electrodes. By the method of electrochemistry, the electrochemical behaviors of dopamine (DA) and ascorbic acid (AA) on the modified electrodes were in studied. Selective detection of DA in the presence of AA was realized. There are four sections in this paper as below:1.The define , sypes, preparation, superficial analysis and applications of chemically modified electrodes were reviewed. In addition , the amino acids, dopamine and ascorbic acid were introduced.2. A covalent modified glassy carbon electrode with L-Lysine and L-Tyrosine have been fabricated via an electrochemical oxidation procedure. An electroactive redox probe Fe(CN)₆^3-/4- was chosen to investigate the electrochemical behavior, stability and reproducibility of the modified electrodes .The method of electrochemical impedance spectroscopy has been employed to characterize the surface layer. The overlay of electrodes were calculated. The L-Lysine was 94.5% and the L-Tyrosine was 95.9%.3. First, the behaviors of DA and AA on the L-Lysine modified glassy carbon electrode(Lys/GCE) were studied by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) . The experiment results indicated that Lys/GCE not only can improve the electrochemical behaviors of DA and AA, but also can resolve the mixed voltammetric response of DA (pKa=8.82) and AA (pKa=4.12) at GCE into two well-defined voltammetric peaks. The separation between the two peak potentials was about 507 mV in CV and 460 mV in DPV, which was large enough for the determination of DA in the presence of AA. The cationic DA can get access to the electrode surface and the anionic AA is resisted to get to the electrode suiface. Because of the electrostatic interactions, the mixed voltammetric response of DA and AA at GCE can be resolved into two well-defined voltammetric peaks. In addiction, the behaviors of DA and AA on the L-Tyrosine modified glassy carbon electrode (Tyr/GCE)was studied also use the method of CV and DPV . Tyr/GCE can also improve the electrochemical behaviors of DA and AA and because of electrostatic interactions the mixed voltammetric response of DA and AA...