title: Using mass spectrometry to highlight structures of degradation compounds obtained by photolysis of chloroacetamides: case of acetochlor.
abstract: The photooxidation of acetochlor (a pesticide belonging to the acetamides group) using a polychromatic UV irradiation in ultrapure water was studied. This study reports the efficiency of mass spectrometry for the characterization of photodegradation products of acetochlor. Decompositions of protonated ions MH+are proposed in electrospray (ESI) mode for LC–MS, while electron ionization (EI) and chemical ionization modes (CI) are used for GC–MS. The knowledge of fragmentation and the use of a combination of experiments (MS/MS, high resolution) allow the characterization of photoproducts. Structural elucidation is assisted by the use of photolysed deuterated compounds. Fifteen major degradation products have been characterized, five by LC-QTOF, six photoproducts by GC-ITMS, and four are observed by both techniques. In vitro bioassays based on the quantification of receptor-mediated activity demonstrated that acetochlor photolysis engenders a moderate but significant estrogenic activity. Moreover, a quantitative structure–activity relationship (QSAR) approach was used to assess the potential toxicity effect of acetochlor and its by-products. The predictions were analyzed showing a variety of toxicity profiles of acetochlor photoproducts depending on the toxicological investigated endpoint.
authors.forename: Yasmine
authors.initials: Y
authors.lastname: Souissi
authors.forename: Sophie
authors.initials: S
authors.lastname: Bourcier
authors.forename: Sélim
authors.initials: S
authors.lastname: Ait-Aissa
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Maillot-Maréchal
authors.forename: Stéphane
authors.initials: S
authors.lastname: Bouchonnet
authors.forename: Christophe
authors.initials: C
authors.lastname: Genty
authors.forename: Michel
authors.initials: M
authors.lastname: Sablier
mesh_terms: D000081:Acetamides / Q000737:chemistry*; D000818:Animals; D045744:Cell Line, Tumor; D002853:Chromatography, Liquid / Q000379:methods; D003198:Computer Simulation; D003530:Cyprinidae; D003621:Daphnia; D004967:Estrogens / Q000737:chemistry / Q000633:toxicity; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D015233:Models, Statistical; D010573:Pesticide Residues / Q000737:chemistry* / Q000528:radiation effects / Q000633:toxicity; D010782:Photolysis; D051381:Rats; D053719:Tandem Mass Spectrometry / Q000379:methods*; D014052:Toluidines / Q000737:chemistry* / Q000528:radiation effects / Q000633:toxicity; D018675:Toxicity Tests; D014874:Water Pollutants, Chemical / Q000737:chemistry* / Q000528:radiation effects / Q000633:toxicity
chemical_list: D000081:Acetamides; D004967:Estrogens; D010573:Pesticide Residues; D014052:Toluidines; D014874:Water Pollutants, Chemical; C013874:chloroacetamide; C043377:acetochlor