A similar behavior was observed for phenol by Enache and Oliviera-Brett and Stević et al. for 8-hydroxyquinoline. At the same time, as these peaks appear, the main oxidation peak current decreases with subsequent cycles due to the adsorption of TDMQ20 oxidation products on the GCE surface. Based on these measurements and the reports in the literature, we can conclude that the oxidation of TDMQ20 results in the formation of a redox-active chemisorbed species whose redox potential is lower than that of the TDMD20 molecule itself. In order to confirm our thesis, we performed a study using bidimensional thin-layer UV-Vis SEC, which will be described in the next section.