Elimination voltammetry of short oligonucleotides

Oligonucleotides containing adenines (A) or cytosines (C) yield reduction voltammetric peaks on mercury electrodes. The peak potentials of both bases are located very close to each other on the potential scale, so that usually only one voltammetric peak is observed. One signal only can be observed even when adsorptive transfer stripping voltammetry (AdTSV) is used. In the present work we have used elimination voltammetry with linear scan (EVLS) in connection with hanging mercury electrode, and shown that this electrochemical method is able to distinguish the two signals. EVLS is based on elimination of one or two selected currents from total currents measured by linear scan voltammetry. The function eliminating kinetic and charging currents, and conserving the diffusion current was calculated for the case of adsorbed electroactive substance. The theoretical elimination curve has a peak-counterpeak form. This elimination function was applied to the analysis of short oligonucleotides containing A and C in their molecules. The height and shift of EVLS signals were affected by pH, buffer components, the content of A and C, and the time of accumulation. Our results showed that the voltammetric signal of C can be separated from the signal of A, and that EVLS in connection with AdTSV is a promising tool for qualitative and quantitative studies of homo- and hetero-oligonucleotides.