Characterization of pesticide-β-cyclodextrin inclusion complexes in aqueous solution

Abstract

The solubility of four different pesticides, "dimethoate", "simazine" "linuron" and "thiram", poorly soluble or non-soluble in water, were measured in water and in aqueous solution of ?-cyclodextrin by ultraviolet spectrophotometry. Standard water solutions of pesticides were prepared in the range of concentrations up to the maximum solubility of each pesticide in water. Concentrations of the pesticides were determined as absorbance on the absorption maximum. The obtained results show that the aqueous solution of ?-cyclodextrin was a powerful solubilizer of investigated pesticides due to the formation of inclusion complexes. Effective solubility of some of the pesticides in aqueous ?-cyclodextrin solution was up to three orders of magnitude higher than those in water. Thermodynamic parameters and complex stability constant of the obtained inclusion complexes were determined by the calorimetric measurements.Promena rastvorljivosti u vodenom rastvoru ?-ciklodekstrina cetiri razlicita pesticida: dimetoata, linurona, simazina i cirama; veoma slabo rastvornih ili nerastvornih u vodi, odredjivana je primenom UV spektrofotometrije. Standardni rastvori pesticida pripremljeni su u opsegu koncentracija do maksimalne rastvorljivosti svakog pesticida u vodi. Koncentracija pesticida odredjivana je merenjem apsorbancije na polozaju apsorpcionog maksimuma. Dobijeni rezultati ukazuju da se rastvorljivost ispitivanih pesticida u vodenom rastvoru ?-ciklodekstrina u mnogome povecava gradjenjem inkluzionih kompleksa. Efektivna rastvorljivost nekih pesticida je porasla za tri reda velicine. Termodinamicki parametri i konstante stabilnost nastalih inkluzionih kompleksa odredjivani su kalorimetrijskim merenjima.