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

A literature survey reveals that the values of the equilibrium constan ts 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 prob lem of the reliability of binding constants. We report here our emf st udies of the inclusion of cetyltrimethylammonium bromide and tetradecy ltrimethylammonium bromide with alpha- and beta-cyclodextrin and compa re these data with other independent studies. The potential of the iso thermal titration calorimetry as a method to determine these constants is also examined. We conclude that techniques which yield direct meas urements of ''free'' and ''included'' surfactant and also isothermal t itration calorimetry appear to give results which are consistent.