Application of thin film dialysis to the determination of equilibrium constants

A theoretical basis for thin-film dialysis involving binding between a ligand and nondialyzing species is presented. A general differential equation that applies to the case of equivalent, noninteracting sites is derived relating [A]_F, [A]_T, [P]_T, and K. Numerical solutions to this equation are used to develop a series of escape curves corresponding to specific values of the parameters [P]_T, [A]_i, K, and k₀. A general method for determining an equilibrium binding constant from thin-film dialysis data is given. A comparison of thin-film dialysis results predicted by this theory with literature data shows essential agreement.