A CV was performed to study the oxidation of TDMQ20 with Bidim-SEC. The results are shown in Figure . Figures and represent the contour plot of all the UV-Vis spectra registered during the experiment in normal and parallel configurations. For clarity, the CV is also represented in Figure . The CV obtained using C-SPE as electrode is slightly different to the one acquired using GCE. In this case, the second peak of oxidation, which was called Eox2 in Figure , is better defined in the CV performed on C-SPE (Figure ) which is most likely related to the slightly different surface structure of GC and C-SPE. Usually, the electron transfer is sluggish on C-SPEs respect to a GC electrode. During the backward scan, the reversible reduction of absorbed species is observed, as discussed in Figure . As can be seen in Figure and C, during the oxidation of TDMQ20, noticeable changes in the parallel and normal UV-Vis spectra are registered. At 261 nm, corresponding with the absorbance maximum of TDMQ20 (Figure ), a noticeable negative band is observed, which decreases during TDMQ20 oxidation. The presence of a negative band in UV-Vis-SEC indicates that a reactant has been consumed in the electrochemical process, since the reference spectrum is defined at the beginning of the experiment, being the solution containing TDMQ20 (therefore, changes of absorbance are measured). This band is observed in normal and parallel configuration, indicating that the TDMQ20 present in the solution is disappearing during its oxidation, as expected. Some variations of the absorbance at this wavelength can be observed at negative potentials, which will be discussed later.