title: Oxidation of danofloxacin by free chlorine-kinetic study, structural identification of by-products by LC-MS/MS and potential toxicity of by-products using in silico test.
abstract: In this study, we aimed to investigate the kinetics and the mechanism of reaction of the fluoroquinolone antibacterial danofloxacin (DANO) by free available chlorine (FAC) during water chlorination process. Kinetic study was thus performed at pH 7.2, 20 °C in the presence of an excess of total chlorine. Under these experimental conditions, a second-order reaction rate constant (first-order relative to DANO concentration and first-order relative to FAC concentration) was evaluated to k~1446 M-1s-1. Five degradation products were identified at different reaction times. Their structures were investigated by using fragmentations obtained at different CID collision energies in MS/MS experiments. Moreover, the toxicity of the proposed structures was predicted by using T.E.S.T.
  
  
  METHODS
  The results indicated that all by-products may have a developmental toxicity. The oral rat LD50concentration was predicted to be lower than that of DANO. Furthermore, two degradation compounds presented a concentration level for fathead minnow LC50(96 h) lower than that of DANO and presented toxicity for the marine animals.
authors.affiliation: National Council of Scientific Research (CNRS)-Lebanese Atomic Energy Commission (LAEC), Laboratory of Analysis of Organic Pollutants (LAOP), 11-8281, Riad El Solh, Beirut, 1107 2260, Lebanon.|EPOC, L'équipe de Physico et Toxico Chimie de l'Environnement, University of Bordeaux, UMR 5805, 33400, Talence, France.|CNRS, EPOC, UMR5805, 33400, Talence, France.|Dr. Faculté de Santé Publique, Section I, Hadath, Beyrouth, Lebanon.
authors.forename: Montaha
authors.initials: M
authors.lastname: Yassine
authors.affiliation: National Council of Scientific Research (CNRS)-Lebanese Atomic Energy Commission (LAEC), Laboratory of Analysis of Organic Pollutants (LAOP), 11-8281, Riad El Solh, Beirut, 1107 2260, Lebanon.
authors.forename: Ahmad
authors.initials: A
authors.lastname: Rifai
authors.affiliation: Dr. Faculté de Santé Publique, Section I, Hadath, Beyrouth, Lebanon.
authors.forename: Samah
authors.initials: S
authors.lastname: Doumyati
authors.affiliation: EPOC, L'équipe de Physico et Toxico Chimie de l'Environnement, University of Bordeaux, UMR 5805, 33400, Talence, France.|CNRS, EPOC, UMR5805, 33400, Talence, France.
authors.forename: Aurélien
authors.initials: A
authors.lastname: Trivella
authors.affiliation: EPOC, L'équipe de Physico et Toxico Chimie de l'Environnement, University of Bordeaux, UMR 5805, 33400, Talence, France.|CNRS, EPOC, UMR5805, 33400, Talence, France.
authors.forename: Patrick
authors.initials: P
authors.lastname: Mazellier
authors.affiliation: EPOC, L'équipe de Physico et Toxico Chimie de l'Environnement, University of Bordeaux, UMR 5805, 33400, Talence, France.|CNRS, EPOC, UMR5805, 33400, Talence, France.
authors.forename: Hélène
authors.initials: H
authors.lastname: Budzinski
authors.affiliation: National Council of Scientific Research (CNRS)-Lebanese Atomic Energy Commission (LAEC), Laboratory of Analysis of Organic Pollutants (LAOP), 11-8281, Riad El Solh, Beirut, 1107 2260, Lebanon. mohamad_isk@hotmail.com.|Dr. Faculté de Santé Publique, Section I, Hadath, Beyrouth, Lebanon. mohamad_isk@hotmail.com.
authors.forename: Mohamad
authors.initials: M
authors.lastname: Al Iskandarani
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000633:toxicity; D002713:Chlorine / Q000737:chemistry*; D002853:Chromatography, Liquid; D003198:Computer Simulation; D003530:Cyprinidae; D024841:Fluoroquinolones / Q000737:chemistry / Q000633:toxicity; D054879:Halogenation; D007700:Kinetics; D007928:Lethal Dose 50; D008962:Models, Theoretical; D010084:Oxidation-Reduction; D051381:Rats; D053719:Tandem Mass Spectrometry; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000633:toxicity; D018508:Water Purification / Q000379:methods
chemical_list: D000900:Anti-Bacterial Agents; D024841:Fluoroquinolones; D014874:Water Pollutants, Chemical; C068581:danofloxacin; D002713:Chlorine
keywords: Chlorination; Danofloxacin; Degradation pathways; Degradation products; Kinetic study; Toxicity prediction