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- Title
Isomerization of fenbuconazole under UV-visible irradiation - chemical and toxicological approaches.
- Authors
Lassalle, Yannick; Nicol, Edith; Genty, Christophe; Bourcier, Sophie; Bouchonnet, Stéphane
- Abstract
RATIONALE: Fenbuconazole is a fungicide commonly used for the protection of vineyards, vegetables and grain crops. Under UV-visible irradiation, it undergoes isomerization through various cyclization processes. Isomeric structures were elucidated by liquid chromatography/high-resolution multiple-stage mass spectrometry (LC/HR-MSn) coupling. The potential toxicities of these isomers were estimated by in silico tests. METHODS: Aqueous solutions of fenbuconazole and grapes treated with this fungicide were irradiated in a self-made reactor equipped with a mercury vapor lamp. Analyses were carried out using high-performance liquid chromatography (HPLC) coupled with Fourier transform ion cyclotron resonance mass spectrometry (FT-ICRMS). High-resolution m/z measurements, multiple-stage mass spectrometry and isotopic labeling experiments allowed structural elucidation of the isomers of fenbuconazole. In silico toxicity estimations were carried out using the T.E.S.T. program. RESULTS: Seven isomers of fenbuconazole were detected after irradiation of the fungicide in aqueous solution; the major ones were also detected in the flesh of treated grapes irradiated under laboratory conditions. Elucidation of their chemical structures owing to high resolution measurements and multi-stage collision induced dissociation experiments allowed confirmation of photo-transformation pathways mainly dominated by cyclization processes. Photo-induced isomers exhibited higher potential toxicities than fenbuconazole for Daphnia magna and fathead minnow species. CONCLUSIONS: UV-visible irradiation of fenbuconazole in aqueous solution and on grapes leads to the formation of isomers, all of which being potentially much more toxic than the parent fungicide.
- Subjects
FENBUCONAZOLE; ISOMERIZATION; ULTRAVIOLET-visible spectroscopy; IRRADIATION; LIQUID chromatography-mass spectrometry; AQUEOUS solutions
- Publication
Rapid Communications in Mass Spectrometry: RCM, 2015, Vol 29, Issue 14, p1335
- ISSN
0951-4198
- Publication type
Article
- DOI
10.1002/rcm.7227