H114 Journal of The Electrochemical Society, 161 (3) H114-H120 (2014) 0013-4651/2014/161(3)/H114/7/$31.00 © The Electrochemical Society Chronopotentiometry Insight into Acid-Base Equilibria between Phosphatidylcholine Bilayer and Ions from Electrolyte Sol

This paper discusses the effect of adsorption of hydrogen and hydroxide ions which are present in the solution upon electrical capacitance and electrical resistance of the bilayer membrane formed by phosphatidylcholine. Both electrical parameters of the membrane were determined as a function of pH from chronopotentiometric measurements. Two descriptions were tested to explain the phenomena occurring on the bilayer surface. The descriptions display changes in the capacitance and the resistance values, particularly in the ranges distant from the isoelectric point. In Description I, the surface is continuous with uniformly distributed functional groups constituting the centers of H+ and OH − ion adsorption. In Description II, the surface is built of lipid molecules, free or with adsorbed H+ and/or OH − ions. In both descriptions the contributions of the individual lipid molecule forms to the electrical parameters of the membrane were assumed to be additive. Theoretical equations were derived to describe the electrical parameters as a function of pH for proposed descriptions