Voltammetric Study of Adenine Complex with Copper on Mercury Electrode

Abstract

The determination of adenine (Ade), adenosine (Ado) and hydrolyzed adenosine (h-Ado) in the presence of copper(II) ions is described by cyclic (CV) and elimination voltammetry with linear scan (EVLS) in connection with adsorptive stripping technique. Signals of adenine and copper-adenine complex were measured on a hanging mercury drop electrode (HMDE) in buffered solutions with different pH. The differences in electrochemical behavior of Ade and Ado were found not only in dependence on the presence of copper ions, scan rate, Ade concentration and pH, but also on the accumulation time and potential where a copper-Ade complex is formed. A deeper evaluation of voltammetric responses was carried out by EVLS. The EVLS function E4 eliminating charging and kinetic current components and conserving the diffusion current component was capable of enhancing the current sensitivity of CV peaks and of detecting electron transfer in adsorbed state. The irreversible electrode process of a totally adsorbed electroactive species is indicated by means of a peak-counterpeak signal. Our results show that EVLS in connection with the adsorptive stripping procedure is not only a useful tool for both qualitative and quantitative microanalysis of Ade but also for revealing certain details in electrode processes.

Voltammetric Study of Aminopurines on Pencil Graphite Electrode in the Presence of Copper Ions

“…Figure 4 shows that both oxidation processes take place in the adsorbed state (peak-counterpeaks) and EVLS signals are about 7 times higher compared to LSVones. The highest EVLS signal was observed for Ade -similar to the experiments performed in connection with the mercury electrode [8]. Moreover, EVLS results confirmed the presumptions under points 3, 4, and 5 of the abovementioned scheme.…”

“…in BAP) is not limiting for the formation of the Cu(I)-purine complex. According to both presented and previous results it can be assumed that the complex formation involves not only nitrogen in position 9, but also the nitrogen atom of the pyrimidine ring [8]. This statement will be the subject of our further investigation.…”

“…As in the previous papers [8,20], elimination voltammetry in connection with the adsorptive stripping technique (AdSV EVLS) was used. While in the case of a mercury electrode the reduction of both Cu (I) -adenine complex and adenine took place, in the case of a PeGE electrode we were able to observe their oxidation processes.…”

“…It was found that sensitive signals provide sparingly soluble complexes of Ade with Cu(I) which are accumulated at the electrode surface, whereas Cu(I) ions can be produced either by reduction of Cu(II) or by oxidation of the Cu-amalgam with a very low detection limit [2,9]. In our previous paper we investigated Ade, adenosine (Ado) and hydrolyzed adenosine (h-Ado) in the presence of copper(II) ions by cyclic (CV) and elimination voltammetry with linear scan (EVLS) [8]. Signals of adenine and copper-adenine complex were measured on a hanging mercury drop electrode in buffered solutions with different pH.…”

“…The EVLS function E4 eliminating charging and kinetic current components and conserving the diffusion current component was capable of enhancing the current sensitivity of CV peaks and of detecting electron transfer in the adsorbed state. The irreversible electrode process of a totally adsorbed electroactive species was indicated by a peak-counterpeak signal [8].…”