F. Barbato et al., Inclusion complexation of carbaryl and beta-cyclodextrin in solution and in the solid state, J INCL P MA, 38(1-4), 2000, pp. 423-433
Citations number
21
Categorie Soggetti
Chemistry
Journal title
JOURNAL OF INCLUSION PHENOMENA AND MACROCYCLIC CHEMISTRY
This study was carried out with the aim of investigating the interactions b
etween beta-cyclodextrin and carbaryl, a carbamate pesticide, and their eff
ect on some physico-chemical properties of carbaryl, such as aqueous solubi
lity and lipophilicity. The interactions between carbaryl and beta-cyclodex
trin were thoroughly investigated both in solution and in the solid state.
The effect of beta-cyclodextrin on the aqueous solubility of carbaryl was e
valuated by the phase solubility method. The amount of carbaryl dissolved i
ncreased linearly with the addition of beta-cyclodextrin according to an A(
L) type plot and without precipitation of the complex. The apparent stabili
ty constant of the complex was 289 +/- 21 M-1, assuming a 1 : 1 stoichiomet
ry; this value was confirmed by a method based on circular dichroism measur
ements. Equimolar carbaryl/beta-cyclodextrin solid systems were prepared by
physical-mixing and freeze-drying, and fully characterised by Differential
Scanning Calorimetry, X-ray powder diffractometry and Fourier Transform In
fra-Red analysis. The results of the solid state study demonstrated that th
e freeze-drying method yields a system with a high degree of amorphisation
and yields an inclusion complex. The dissolution profile of the pesticide w
as affected by the physico-chemical properties of each solid system, the fr
eeze-dried form dissolving more rapidly. However, the physical association
of beta-cyclodextrin and carbaryl enhanced the aqueous solubility of the in
secticide as well.