title: Structural elucidation and estimation of the acute toxicity of the major UV-visible photoproduct of fludioxonil - detection in both skin and flesh samples of grape.
abstract: Ultraviolet (UV)-visible irradiation of fludioxonil was investigated with two photoreactors using either a mercury or xenon vapor lamp. In both cases, it led to the formation of only one photoproduct in significant amount: 2-(2,2-difluorobenzo[d][1,3]dioxol-4-yl)-2-(nitrosomethylene)-4-oxobutanenitrile, which has been characterized using Liquid Chromatography - High Resolution - Tandem Mass Spectrometry (LC-HR-MS/MS) coupling. A photolysis pathway has been proposed to rationalize its formation in degassed water. In vitro bioassays on Vibrio fischeri bacteria showed that UV-vis irradiation of an aqueous solution of fludioxonil significantly increases its toxicity. Because no other by-product was detected in significant amount, the photoproduct mentioned above may be considered mainly responsible for this increase in toxicity. Grape berries treated with a 50 ppm aqueous solution of fludioxonil were submitted to UV-visible irradiation under laboratory conditions. The fungicide and photoproduct were detected in both skin and flesh of berries, even after they have been rinsed with water. The ability of the photoproduct to pass through the fruit skin is comparable with that of fludioxonil. These results are of concern for consumers because they mean that water tap rinsing does not lead to efficient removing of both compounds.
authors.affiliation: Laboratoire de Chimie Moléculaire - UMR 9168, École Polytechnique, Palaiseau Cedex, 91128, France.
authors.forename: Yannick
authors.initials: Y
authors.lastname: Lassalle
authors.affiliation: Laboratoire de Chimie Moléculaire - UMR 9168, École Polytechnique, Palaiseau Cedex, 91128, France.
authors.forename: Édith
authors.initials: É
authors.lastname: Nicol
authors.affiliation: Laboratoire de Chimie Moléculaire - UMR 9168, École Polytechnique, Palaiseau Cedex, 91128, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Genty
authors.affiliation: Laboratoire de Chimie Moléculaire - UMR 9168, École Polytechnique, Palaiseau Cedex, 91128, France.
authors.forename: Sophie
authors.initials: S
authors.lastname: Bourcier
authors.affiliation: Laboratoire de Chimie Moléculaire - UMR 9168, École Polytechnique, Palaiseau Cedex, 91128, France.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Bouchonnet
mesh_terms: D048908:Aliivibrio fischeri / Q000187:drug effects; D004149:Dioxoles / Q000032:analysis / Q000737:chemistry / Q000528:radiation effects* / Q000633:toxicity*; D005638:Fruit / Q000737:chemistry*; D005659:Fungicides, Industrial / Q000737:chemistry / Q000528:radiation effects / Q000633:toxicity*; D010782:Photolysis; D011758:Pyrroles / Q000032:analysis / Q000737:chemistry / Q000528:radiation effects* / Q000633:toxicity*; D014466:Ultraviolet Rays; D027843:Vitis / Q000737:chemistry*
chemical_list: D004149:Dioxoles; D005659:Fungicides, Industrial; D011758:Pyrroles; C108339:fludioxonil
keywords: LC-MS/MS; Vibrio fischeri; fludioxonil; in vitro tests; photolysis; structural elucidation