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 trans formed to a white powder form, which gives the opportunity to formulat e the complex as a stabilized dust. In gamma CD complex form, DCPE is ''packed'' into a hydrophilic cover, so that its affinity to hydrophob ic surfaces is decreased and therefore its dermal absorption during ap plication reduced. The stoichiometry coefficient of the inclusion comp lex is found to be 1:1. Differential scanning calorimetry and X-ray po wder diffraction analysis have been used to confirm the inclusion in s olid state. H-1 NMR has been used for proving the complexation in aque ous 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 comple x was determined kinetically.