Abstract
Disadvantage of some organic pesticides is their low water solubility. Among other substances, cyclodextrins and modified cyclodextrins were considered as agents for improving pesticides water solubility. The solubility of poorly soluble pesticides, dimethoate, simazine, linuron and thiram, was determined in aqueous solution of methylated-?-cyclodextrin (mbCD) by ultraviolet spectrophotometry. Methylated-?-cyclodextrin was obtained by the modified Hawort method and characterized by 1H NMR and HPLC data. The average degree of substitution was 13.8. Methylation was done either on C-2, C-3, and C-6 atoms of glucopyranose unit therefore obtained product can be assort as randomly m?CD. Solubility of the studied pesticides in aqueous solution of m?CD increases in relation to their solubility in water for dimethoate 506, for simazine167, for thiram 44, and for linuron 20 times. Reactions of dimethoate and simazine with m?CD were entropy-driven while the inclusion complexation of m?CD with the linuron and thiram were driven by both, enthalpy and entropy, as determined by calorimetric measurements. The observed solubility increment of the investigated pesticides in aqueous solution of m?CD, suggests that it can be efficiently used in pesticide solutions formulations and increase their bioavailability, and biodegradability.
Highlights
The disadvantage of some organic pesticides is their low water solubility
Continuing our investigation on properties and applications of cyclodextrins [13,14], we report the methylation of the β-cyclodextrin, characterisation of obtained methylated β-cyclodextrin (mβCD), and its complexation with poorly soluble pesticides, dimethoate, simazine, linuron and thiram
There are no significant differences in the position of the absorption bands between pesticides solutions in water and in the aqueous methylated β-cyclodextrin solutions due to very weak intermolecular bonds between “host” and “guest” molecules [17]
Summary
The disadvantage of some organic pesticides is their low water solubility. Among other substances, cyclodextrins and modified cyclodextrins were considered as agents for improving pesticide water solubility. G.M. PETROVIĆ et al.: COMPLEXES OF PESTICIDES IN SOLUTIONS OF METHYLATED β-CYCLODEXTRIN Continuing our investigation on properties and applications of cyclodextrins [13,14], we report the methylation of the β-cyclodextrin, characterisation of obtained mβCD, and its complexation with poorly soluble pesticides, dimethoate, simazine, linuron and thiram.
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