Electrochemical behavior and in vivo determination of the neurotransmitterdopamine using sodium montmorillonite modified electrodes

A modified glassy carbon electrode is used to examine the mass transport ch aracteristics of the neurotransmitter dopamine (DA) in sodium montmorilloni te films. The apparent diffusion coefficient (D-app) of DA in the film is m easured by chronocoulometry and cyclic voltammetry to be 2.3 x 10(-9) and 5 .1 x 10(-9) cm(2)/s. According to the Nicholson theory, the standard rate c onstant (k(s)) of heterogeneous electron transfer reaction for DA is estima ted to be 2.7 x 10(-6) cm/s by cyclic voltammetry. Montmorillonite has been modified on carbon fiber electrodes, and voltammetric response of some neu rotransmitters and their metabolites has been examined. The variation of DA concentration in a rat brain with decreasing blood supply has been detecte d when the modified microelectrode is used in in vivo experiments.