Interaction of Some Pharmaceuticals with Macromolecules II: Binding of Certain Benzoic Acid Derivatives by Polysorbate 80 and Cetomacrogol 1000

Abstract

The magnitude of intermolecular association occurring in aqueous solution between benzoic acid, a series of amino-, chloro-, and hydroxybenzoic acids, and two macromolecules, polysorbate 80 and cetomacrogol 1000, was determined by means of an equilibrium dialysis technique. All the benzoic acids studied were found to exhibit reversible association with the surfactants of the polyether type. The degree of interaction between the aromatic acids and the macromolecules appears to be dependent upon the type of functional group and its position in the interacting molecule. The binding affinity of polysorbate 80 for benzoic acid decreased with an increase in pH. The binding of the benzoic acids by polysorbate 80 and cetomacrogel 1000 was found to be describable by a Freundlich-type adsorption relationship. The magnitude of intermolecular association occurring in aqueous solution between benzoic acid, a series of amino-, chloro-, and hydroxybenzoic acids, and two macromolecules, polysorbate 80 and cetomacrogol 1000, was determined by means of an equilibrium dialysis technique. All the benzoic acids studied were found to exhibit reversible association with the surfactants of the polyether type. The degree of interaction between the aromatic acids and the macromolecules appears to be dependent upon the type of functional group and its position in the interacting molecule. The binding affinity of polysorbate 80 for benzoic acid decreased with an increase in pH. The binding of the benzoic acids by polysorbate 80 and cetomacrogel 1000 was found to be describable by a Freundlich-type adsorption relationship.