Linear-sweep Voltammetry and the Simultaneous Determination of Purine Bases and Their Nucleosides in the Glassy Carbon Electrode

Abstract

Adenine, adenosine, guanine, and guanosine were voltammetrically oxidized in a glassy carbon electrode in aqueous solutions, but at different potentials. In general, the nucleosides were oxidized at more positive potentials than their bases. The bases and their nucleosides were strongly adsorbed on the surface of the glassy carbon electrode at the pH values around neutrality, so that the concentration vs. anodic peak current curves were not linear. The adsorption on the electrode was very dependent on the pH, and at pH values below 4 good linear relationships were observed between the anodic peak current and the concentration. The differences between the peak potentials of each of the purine bases and their nucleosides were most pronounced at pH 2–4. Consequently, it was possible to determine simultaneously both in mixtures of the purine bases and their nucleosides by using Britton-Robinson buffer as a supporting electrolyte in the pH range of 2–4. The proposed method is simple and rapid, since no prior treatment or separation procedure is required.

Electrochemistry of Purine Derivatives 1: Direct Determination for the Antiviral Drug 9-[(1,3-Dihydroxy-2-propoxy)methyl]guanine by Anodic Differential Pulse Voltammetry

“…Compound 1 gave a single, well-defined oxidation peak over the pH range (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12) investigated ( Fig. 1).…”

“…[1][2][3][4][5] The redox chemistry of these nitrogen heterocycles is important because they constitute the essential components of polynucleic acids and other biologically important compounds, such as ATP and GTP. In addition, some authors have suggested that the electrochemical and enzymatic oxidations of purines follow similar mechanistic pathway^.^,^ It was therefore of interest to examine the electrochemistry of a recently developed deoxyguanosine analogue, 9-[1,3-dihydroxy-2-propoxymethyl]guanine ( l).7 This compound is a potent antiviral agent with a broad range of activity against herpes simplex virus types 1 and 2,*3 cytomegalovirus,g.…”

“…'~ Guanine and adenine both oxidize voltammetrically over a wide pH range's and have been determined quantitatively in the presence of their nucleosides a t a glassy carbon electrode by linear sweep techniques. 3 Difficulties in achieving reproducible surface states and relatively high background currents that result from voltage scanning have (until recently) hampered quantitative assays in which solid electrodes are used.1620 The variability encountered with solid electrode surfaces often requires extensive pretreatment (polishing) between successive scans as well as compensation for the magnitude and alteration in background signal, especially in aqueous media.19…”

A Pencil Graphite Electrode In Situ Modified by Monovalent Copper: a Promising Tool for the Determination of Methylxanthines

“…The anodic signal of xanthine and some methyl-substituted xanthines was studied on carbon electrodes and the results were summarized in details by Dryhurst [4]. It was supposed that the oxidation of these purine derivatives involves electron exchange at carbon C8 and nitrogen N7 at higher oxidation potentials [5][6][7]. The electrooxidation of these substances was studied later by the authors [8][9][10][11][12], who revised the previous results, suggested a detailed oxidation mechanism and described the effect of methyl groups on the oxidation of xanthine [13][14][15][16].…”

Electrochemistry and Voltammetric Determination of Adenosine with N‐Hexylpyridinium Hexafluorophosphate Modified Electrode

“…Electrochemical method had also been devised for the detection of adenosine. Yao et al [8] reported the simultaneous determination of purine bases and their nucleosides at glassy carbon electrode. However the electrooxidation of adenosine on the common working electrode showed high oxidation potential and limited sensitivity.…”