Pulse Polarographic Studies on the Adsorption of Adenine, Adenosine and Mono, Di and Triphosphate of Adenosine

Abstract Adenine, adenosine and adenine mononucleotides (3′‐AMP, 5′‐AMP, 5′‐ADP and 5′‐ATP) were studied at various pH values by means of normal pulse polarographic measurements at the dropping mercury electrode. It was found that adenine, adenosine and adenine mononucleotides yield pulse polarographic peak. From its height and potential conclusions can be made about their adsorption effects at the charged interface. Adsorption effects in normal pulse polarography of adenine, adenosine and adenine mononucleotides were also investigated through the dependence of the pulse polarographic current on various parameters such as pH, temperature, adsorption time and bulk concentration of depolarizer. The potential dependence of the pulse peak height is of bell shaped type with an extended maximum region around the potential of electrocapillary maximum (Eecm) of the supporting electrolyte. For the same bulk concentration the pulse peak height decreases in the series adenosine, AMP, ADP and ATP, i.e. with increasing negative charge. Pulse polarography is particularly valuable for calculation of the values of adsorption parameters for the dilute layer (adsorption coefficient b, free adsorption enthalphy ‐ΔG °, interaction coefficient a) provided the span of the drop life before the application of the pulse is adjusted to a period sufficiently long to reach adsorption equilibrium.