To further confirm the 2-electron/2-proton reduction mechanism occurring at pH 3, we recorded spectra for substances similar in structure to the 8AQ molecule. In Figure , we compare spectra for 8AQ when potential was not applied and after applying negative potential during 360 s with those of quinoline (Q) and 1,2,3,4-tetrahydro quinoline (1,2,3,4-Q). The results obtained indicate that 8AQ most probably is not fully reduced to tetrahydro-8-aminoquinoline during the measurement. As on the recorded spectrum (applied negative potential during 360 s) there are no characteristic bands of 1,2,3,4-Q (243, 260 and 267 nm). Thus, based on SEC data and computational studies we can assume that under the tested conditions, the compound Red1 or Red2 is formed.