RELIABILITY OF THE EXPERIMENTAL METHODS TO DETERMINE EQUILIBRIUM-CONSTANTS FOR SURFACTANT CYCLODEXTRIN INCLUSION COMPLEXES

A literature survey reveals that the values of the equilibrium constants for inclusion complexes involving surfactants and cyclodextrins can vary by several order of magnitude for the same system when different experimental methods are employed. In this paper we consider the problem of the reliability of binding constants. We report here our emf studies of the inclusion of cetyltrimethylammonium bromide and tetradecyltrimethylammonium bromide with alpha- and beta-cyclodextrin and compare these data with other independent studies. The potential of the isothermal titration calorimetry as a method to determine these constants is also examined. We conclude that techniques which yield direct measurements of ''free'' and ''included'' surfactant and also isothermal titration calorimetry appear to give results which are consistent.