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.
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-1 s-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.


PROGRAM
The results indicated that all by-products may have a developmental toxicity. The oral rat LD50 concentration 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.
['Yassine|Montaha|M|', 'Rifai|Ahmad|A|', 'Doumyati|Samah|S|', 'Trivella|Aurélien|A|', 'Mazellier|Patrick|P|', 'Budzinski|Hélène|H|', 'Al Iskandarani|Mohamad|M|']
D000818:Animals D000900:Anti-Bacterial Agents D002713:Chlorine D002853:Chromatography, Liquid D003198:Computer Simulation D003530:Cyprinidae D024841:Fluoroquinolones D054879:Halogenation D007700:Kinetics D007928:Lethal Dose 50 D008962:Models, Theoretical D010084:Oxidation-Reduction D051381:Rats D053719:Tandem Mass Spectrometry D014874:Water Pollutants, Chemical D018508:Water Purification
Danofloxacin Chlorination Kinetic study Degradation products Degradation pathways Toxicity prediction