Resolution of overlapped reduction signals in short hetero-oligonucleotides by elimination voltammetry

The resolution of overlapped reduction voltammetric signals of adenine (A) and cytosine (C) residues in short synthetic hetero-oligodeoxynucleotides (ODNs) with different sequences of A and C, but with the same ratio (A/C=1/2), was carried out by elimination voltammetry with linear scan (EVLS). The EVLS, as a mathematical transformation of voltammetric total currents measured at different scan rates, is capable to yield very sensitive resolution of potentially closed signals, which cannot be separated by common electrochemical methods. The best resolution of A and C signals was observed when the EVLS function eliminating the charging and kinetic currents (I-c, I-k) and conserving the diffusion current (I-d) was combined with adsorption stripping technique (AdS). ne resulting peak-counterpeak signal made it possible not only to separate the responses of A and C residues, but also to follow the dynamics of adsorption processes on mercury electrode surfaces. Together with the effect of the accumulation time on peak-counterpeak signal, the effect of pH and temperature on this signal was studied. The relation between elimination signals and the structure changes of ODNs was discussed.