By comparing the evolution of the spectra registered in normal and parallel configurations (Figure B and C), we find no noticeable differences between the spectra. This is counter-intuitive since electrochemistry demonstrates that during TDMQ20 oxidation, a modification of the electrode surface is observed (Figure ). In an ideal system, adsorption processes on the WE should lead to changes in the absorbance in normal configuration during UV-Vis-SEC experiments. The explanation of this apparent paradox is that TDMQ20 can undergo different chemical changes during its oxidation, and many of them do not lead to changes in the UV-Vis spectra. This was proven by Nguyen et al. who demonstrated that oxidation of the aliphatic chain of TDMQ20