Electrochemical determination of adenine and adenosine: adsorption of adenine and adenosine at the pyrolytic graphite electrode

Adenine and adenosine are polarographically reducible from aqueous solution at pH 4.7 at the DME at the same E(1 2 ) and are also voltammetrically oxidizable at the PGE, but at different potentials, adenosine at higher potentials. Competitive adsorption of both compounds at the PGE results in a decrease in the scanning voltammetric oxidation peak of adenine in the presence of adenosine, reaching a constant value when the concentration of the latter is above 6 mM. In mixtures, the sum of the two is obtained by polarography at the DME. Solid adenosine is then added to the solution and the adenine is determined by voltamrnetry at the PGE.