In Situ UV-vis and CD Thin-layer Spectroelectrochemistry Study of the Electrochemical Behavior ofL-Noradrenaline in Alkaline Solution

Electrochemical redox behavior of noradrenaline in alkaline solution on a glassy carbon electrode has been investigated by in situ UV-vis and CD spectroelectrochemistry by using a long optical path thin-layer cell. The experimental data were processed by using a double logarithmic method of analysis together with nonlinear regression which confirmed that the first step in both the oxidation of noradrenaline and reduction of noradrenochrome is a two-electron irreversible process governed by an EE mechanism. The kinetic parameters of the electrode reactions, i.e., charge transfer coefficient and the number of electrons transferred, α1n1 = 0.11 and α2n2 = 0.23, formal potentials modified with kinetics, E10′ = 0.65 (± 0.01) V and E20′ = 0.72 V and standard rate cnstants, k10 = 7.0(± 0.5) × 10−5 cm s−1 and k20 = (± 0.5) × 10−5 cm s−1,for the first and second steps in the oxidation process of noradrenaline, and similarly, α1n1 = 0.33, α2n2 = 0.58, E10′ = 0.37 (± 0.01) V, E0′ = −0.25 (± 0.01) V and k10≈k20 = 1.06 (± 0.05) × 10−4 cm s−1 for the first and second steps in the reduction process of noradrenochrome were also determined.