Determination of the stoichiometry of 2,3-dichlorophenoxyacetic acid beta-cyclodextrin complexes in solution and in solid state

Chemical analysis, DSC and solubility determinations have been applied to t he study of solid inclusion complexes of a pesticide, 2,4-dichlorofenoxyace tic acid (2,4-D) as guest, and beta-cyclodextrin (beta-CD) as host, in orde r to produce experimental evidence of the inclusion process and of the stoi chiometry of the inclusion compound. Three processing methods have been stu died and compared: physical (mechanical) mixing; kneading; and spray-drying . The phase-solubility diagram of complex formation in solution has been al so established. The stoichiometric ratio of the complexes was found to be 1 :1 by solubility and DSC, being confirmed by chemical analysis. Spray-dryin g was found to be most suitable method for preparing the complexes. (C). 19 98 Elsevier Science B.V.