title: Oxidation of ciprofloxacin and enrofloxacin by ferrate(VI): Products identification, and toxicity evaluation.
abstract: Ferrate(VI) (Fe(VI)) has been known to react with emerging organic contaminants containing electron-rich organic moieties, such as phenols, anilines, olefins, reduced sulfur and deprotonated amines. Oxidation of fluoroquinolone antibiotics, ciprofloxacin (CIP) and enrofloxacin (ENR), by Fe(VI) were investigated for their reaction products and toxicity changes as well as biodegradability of these products. Ten products were identified for both CIP and ENR reactions with Fe(VI) using a high-resolution accurate-mass Orbitrap mass analyzer. Structural changes to the CIP and ENR molecule included dealkylation, formation of alcohols and amides in piperazine ring and oxygen transfer to the double bond in quinolone structure. An enamine formation mechanism was tentatively proposed to facilitate the interpretation of CIP and ENR oxidation pathways. Toxicity evaluation using Microbial Assay for toxicity Risk Assessment (MARA) bioassay indicated that Fe(VI) oxidation products of CIP and ENR contributed negligible antibacterial potency and Fe(VI) oxidation treatment can remove the residual toxicity of CIP and ENR impacted source waters. The Fe(VI) oxidation treatment resulted in formation of relatively more biodegradable products (based on in silico assessment) than their corresponding parent compounds. The results showed that Fe(VI) has a good potential to degrade fluoroquinolone antibiotics and their antimicrobial potency in natural waters.
authors: CSIRO Land and Water, Waite Campus, PMB 2, Glen Osmond, South Australia 5064, Australia. Electronic address: Bin.Yang@csiro.au.
authors: Bin
authors: B
authors: Yang
authors: CSIRO Land and Water, Waite Campus, PMB 2, Glen Osmond, South Australia 5064, Australia.
authors: Rai S
authors: RS
authors: Kookana
authors: CSIRO Land and Water, Waite Campus, PMB 2, Glen Osmond, South Australia 5064, Australia.
authors: Mike
authors: M
authors: Williams
authors: State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.
authors: Guang-Guo
authors: GG
authors: Ying
authors: CSIRO Land and Water, Waite Campus, PMB 2, Glen Osmond, South Australia 5064, Australia.
authors: Jun
authors: J
authors: Du
authors: CSIRO Land and Water, Waite Campus, PMB 2, Glen Osmond, South Australia 5064, Australia.
authors: Hai
authors: H
authors: Doan
authors: CSIRO Land and Water, Waite Campus, PMB 2, Glen Osmond, South Australia 5064, Australia.
authors: Anupama
authors: A
authors: Kumar
mesh_terms: D002939:Ciprofloxacin / Q000737:chemistry / Q000302:isolation & purification*; D000077422:Enrofloxacin; D024841:Fluoroquinolones / Q000737:chemistry / Q000302:isolation & purification*; D007501:Iron / Q000737:chemistry*; D008826:Microbial Sensitivity Tests; D010084:Oxidation-Reduction; D018675:Toxicity Tests; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000302:isolation & purification*
chemical_list: D024841:Fluoroquinolones; D014874:Water Pollutants, Chemical; C017311:ferrate ion; D000077422:Enrofloxacin; D002939:Ciprofloxacin; D007501:Iron
keywords: Environmental toxicity; Ferrate(VI); Fluoroquinolones; Oxidation; Transformation products