ANALYTICAL APPLICATIONS OF CATALYTIC PROPERTIES OF MODIFIED CYCLODEXTRINS

This paper describes the evaluation of the catalytic properties of mod ified cyclodextrins for analytical applications. The beta-dimethylcycl odextrin was modified by adding one and two imidazolyl groups at carbo n three positions. The modifications produced enhancements of catalyti c activity for the hydrolysis of p-nitrophenyl acetate at neutral pH b y factors of 1000 or more relative to the unmodified cyclodextrins. Th e catalytic properties of the monosubstituted cyclodextrin were evalua ted for the quantification of p-nitrophenyl acetate in the concentrati on range of 10-90 mumol/L. Results obtained by- equilibrium, initial-r ate, and error-compensating predictive kinetic methods were compared. The equilibrium and predictive kinetic options yielded virtually ident ical results, with linear changes with concentration throughout the ra nge studied and severalfold larger than the initial-rate option and de pendencies on temperature, pH, and catalyst concentration that are 5-1 0-fold smaller than the initial-rate option.