A dynamic method of measuring surface potential change due to binding of bitter substance at monolayer-coated liquid membrane surface

A dynamic method of determining the membrane surface potential change due to a binding of a hydrophobic ion has been presented. The surface potential was determined from the time course of membrane potential under zero electric current during a transition between two steady states in a membrane filter impregnated with a phospholipid and 1-octanol. One of the alkaloids, quinine hydrochloride, was used as a hydrophobic electrolyte. Surface charge density and equilibrium constant for binding of quinine ions with ionizable groups of the phospholipids at the membrane surface were determined from the surface potential according to the Poisson–Boltzmann equation.