Elimination voltammetry of adenine and cytosine mixtures.

The elimination voltammetry with linear scan (EVLS) was used to study adenine and cytosine reduction signals at the mercury electrode. In comparison with the linear scan voltammetry (which provides only one unresolved peak), two elimination functions provide good resolution of individual peaks and significant increase of sensitivity. The first elimination function eliminates the kinetic current (I(k)) and conserves the diffusion current (I(d)). The second elimination function eliminates kinetic and charging currents (I(k) and I(c)) simultaneously and conserves the diffusion current (I(d)). Both functions give two well-resolved peaks of adenine and cytosine in a wide concentration range, while the linear sweep voltammetry gives badly resolved peaks due to hydrogen evolution. The best resolution of peaks is observed in acetate buffer at pH 3.8 and the detection limit for both substances is 500 nM. The concentration dependence of EVLS peak heights for one substance at the constant concentration of the other substance is linear. The peak potentials differ in these elimination functions. The difference in EVLS peak potentials gives the possibility to evaluate alpha n(a). Elimination voltammetry with linear scan contributes to the resolution of cathodic signals of purine and pyrimidine bases at very negative potentials near supporting electrolyte discharge.