Studies on degradation of imazalil enantiomers in soil using capillary electrophoresis

Abstract

A scheme was demonstrated to elucidate the degradation behaviors of the two enantiomers of the fungicide imazalil in soil using cyclodextrin-modified capillary zone electrophoresis. The separation buffer was 50 mmol/L NaH2PO4, 5 mmol/L (NH4)H2PO4, and 5 mmol/L beta-cyclodextrin (pH 3.0). The limits of detection of this CE method were 0.24 and 0.26 microg/mL for (-)- and (+)-imazalil, respectively. Five different soil conditions were investigated in laboratory microcosms: under sunlight; in darkness; under UV irradiation; in sterilized soil; and in soil with wheat planted in it. Radiation, microorganisms, and uptake by wheat benefited the degradation of imazalil in this study. The half-lives (t1/2) of imazalil in soil under the above conditions were 20, 30.5, 11, 27.5, and 21.5 days, respectively. The degradation rate of imazalil in soil under the five different sets of conditions decreased in the order: UV irradiation > sunlight > soil with wheat planted in it > sterilized soil > soil kept in darkness. Imazalil in soil (pH 8.2, slightly alkaline) collected in the suburbs showed non-enantioselective degradation.

Chiral Analysis of Pesticides and Drugs of Environmental Concern: Biodegradation and Enantiomeric Fraction

“…Epoxiconazole biodegradation in soil exhibited greater enantioselectivity at higher pH levels [147]. Conversely, the biodegradation of enilconazole in soil samples at alkaline pH was not enantioselective [148]. Triadimefon-enantioselective biodegradation was observed at acidic and alkaline pH levels in a similar matrix, and in both conditions the (R)-enantiomer was preferentially degraded [150].…”

“…Triadimefon-enantioselective biodegradation was observed at acidic and alkaline pH levels in a similar matrix, and in both conditions the (R)-enantiomer was preferentially degraded [150]. pH's impact on biodegradation has been correlated with enzymatic reactions and microbiological activity and can, consequently, affect the enantioselectivity of the degradative course [148,171]. These results suggest that, as well as for the matrix chemical characteristics, the specific individual structure of a compound has a great impact on its enantioselective behavior during degradative processes, and different outcomes regarding the enantioselectivity may be obtained for compounds that are chemically related.…”

“…Enantioselectivity was observed for all triazole compounds considered, although at different degrees depending on experimental conditions such as aeration and pH range [21,147,148,150,153]. A comprehensive study with fenbuconazole conducted with soil in laboratory incubation experiments monitored not only the biodegradation of the target fungicide but also the formation and biodegradation of two chiral metabolites [21].…”

Cyclodextrins in capillary electrophoresis enantioseparations – Recent developments and applications

“…The results were verified by HPLC-MS. The degradation of imidazalil in soil samples was studied by EKC using 50 mM sodium phosphate buffer, pH 3.0, containing 5 mM b-CD [178]. No enantioselective degradation was observed under various laboratory conditions in soil samples collected from city suburbs.…”

Stereoselectivity in bioaccumulation and excretion of epoxiconazole by mealworm beetle (Tenebrio molitor) larvae

“…Moreover, approximately 40 percent of the pesticides are chiral with one or more chiral centers, which have at least a pair of stereoisomers or stereoisomers Xu et al (2011). Although the stereoisomers possess consistent physicochemical properties, they usually exhibit different properties under chiral conditions leading to distinctions in bioactivity, toxicity, Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/ecoenv biological uptake, degradation and metabolic pathways (Chu et al (2007);Garrison (2006)). It means that one enantiomer might be safer in the environment than the other.…”