Spectroelectrochemical and electrochemical behavior of epinephrine at a gold electrode

Spectroelectrochemical and electrochemical behavior of epinephrine, adrenal ine, at a gold electrode was studied with cyclic voltammetric and spectroel ectrochemical techniques. Based on the analysis of a series of spectra obta ined by in-situ spectroscopic measurements absorption bands of possible int ermediates generated in the electrochemical oxidation of adrenaline could b e assigned. Also, assignments of various peaks in the cyclicvoltammograms o btained in different pH conditions are not always in agreement with the pas t findings, especially the formation of dehydrated form of leucoadrenochrom e is not likely to occur under acidic conditions. From the analysis of curr ent voltage curves and simultaneously obtained absorption UV-Vis. spectra, it was able to assign the absorption characteristics of species generated. Adrenalinequinone (lambda = 380 nm) is Formed in the first step of oxidatio n of adrenaline (lambda = 290 nm) followed by cyclization of the quinone pr oduct to produce leucoadrenochrome (lambda = 310 nm). The leucoadrenochrome is finally converted into adrenochrome (lambda = 470 similar to 525 nm) ch emically or electrochemically. Especially, derivative cyclic voltabsorptogr ams (DCVA) of a species obtained by measuring absorbance change with potent ial scans at a selected wavelength provide a new information on the oxidati on of adrenaline. (C) 2000 Elsevier Science Ltd. All rights reserved.