GAMMA-CYCLODEXTRIN INCLUSION COMPLEX OF A NEW ORGANOPHOSPHORUS INSECTICIDE - DETERMINATION OF STABILITY CONSTANT WITH HPLC

The effect of gamma-cyclodextrin (gamma CD) as a complexing agent with a new insecticide (DCPE) has been examined. The liquid DCPE was transformed to a white powder form, which gives the opportunity to formulate the complex as a stabilized dust. In gamma CD complex form, DCPE is ''packed'' into a hydrophilic cover, so that its affinity to hydrophobic surfaces is decreased and therefore its dermal absorption during application reduced. The stoichiometry coefficient of the inclusion complex is found to be 1:1. Differential scanning calorimetry and X-ray powder diffraction analysis have been used to confirm the inclusion in solid state. H-1 NMR has been used for proving the complexation in aqueous solution. gamma CD has a stabilizing effect on DCPE in solutions. In the presence of 2.8 x 10(-3) M gamma CD there is a 2-fold increase in the stability. The association constant of the DCPE/gamma CD complex was determined kinetically.