Ion Adsorption on a Phospholipid Monolayer

To analyze ion adsorption at the phospholipid monolayer at an ITIES, one needs to set up a thermodynamic model. In 2003, Samec et al. proposed a simple model comprising the adsorption of the zwitterionic form L , the formation of the cationic complex RL+ with an aqueous cation R+, and the desorption of the complex in the organic phase and its dissociation in the organic phase [329]. 

The Gibbs adsorption equation includes the contributions from ions of the aqne-ous (RX) and organic (SY) electrolytes, as well as from the zwitterionic (L-) and 

The thermodynamic charge is defined as a difference of surface excesses  

It represents the total charge that is necessary to supply so as to maintain the state of the interface when the interfacial area is increased by a unit amount. Additionally, the interfacial capacitance can also be defined as the curvature of the electrocapillary curve, or can be obtained directly from impedance measurements  

The total surface concentration of phospholipids can be measured by the concentration dependence of the surface tension measurements  

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