Complexation of herbicide bentazon with native and modified beta-cyclodextrin

Abstract

For first time the complexation of bentazon (Btz) with native b-cyclodextrin (b-CD) and modified sulfobutylether- b-CD (SBE-CD) was studied by differential pulse voltammetry. In addition, a spectrophotometry UV–Visible study was carried out. In presence of CDs there is a decrease of the anodic peak current with the increase of the amount of CD. This decrease is due to the lower diffusion coefficient of Btz/CD complex compared with the free guest. Using the variation in current, association constants of 118 ± 20 and 317 ± 25 M-1 for b-CD and SBE-CD were determined. The solubility of bentazon was 8 fold higher with SBE-CD as compared with bentazon-free. Phase solubility diagrams performed using UV–Vis experiments permit to obtain the same association constants which were compared with the values obtained by electrochemical techniques.