Inclusion Complex of Butachlor with β-Cyclodextrin: Characterization, Solubility, and Speciation-Dependent Adsorption
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- 作者：Haitao Bian ; Jingwen Chen ; Xiyun Cai ; Ping Liu ; Huihui Liu ; Xianliang Qiao ; Liping Huang
- 刊名：Journal of Agricultural and Food Chemistry
- 出版年：2009
- 出版时间：August 26, 2009
- 年：2009
- 卷：57
- 期：16
- 页码：7453-7458
- 全文大小：803K
- 年卷期：v.57,no.16(August 26, 2009)
- ISSN：1520-5118
文摘
Due to soil adsorption, higher amounts of the herbicide butachlor are necessary to achieve its herbicidal activity, hence increasing its environmental risks. In this study, the effects of β-cyclodextrin (β-CD) on solubility and soil adsorption of butachlor were investigated. Formation of a 1:1 stoichiometric inclusion complex between them with an apparent stability constant of 443 L mol−1 was confirmed in the solution. Fourier transform infrared spectroscopy showed that the (N−CO) amide bond and alkyl ether moiety of butachlor molecule could enter into the cavity of β-CD, but the double-substituted aromatic ring was excluded because it was larger size than the cavity. Significant enhancing dissolution of butachlor in the inclusion complex occurred in comparison to the free herbicide. The adsorption of butachlor on soil was reduced with an increase of β-CD concentration because of the formation of the inclusion complex with low adsorption potency. Although the sorption distribution coefficient of complexed butachlor (i.e., butachlor/β-cyclodextrin inclusion complex) (Kd,c = 6.14) was about 14% of that of the free herbicide (Kd,f = 44.54), the proportion of the adsorbed amount of complexed butachlor to the total adsorbed amount rose with the increase of β-CD concentration. Thus, the adsorption of inclusion complex cannot be neglected in the presence of high concentrations cyclodextrins, although its water solubility was much higher than that of the free herbicide. These results indicate that β-CD may be used as a formation additive to improve the solubility of butachlor, reduce its adsorption on soil, and increase the availability of butachlor for weeds.