title: Oxidation of antibiotics during water treatment with potassium permanganate: reaction pathways and deactivation.
abstract: Recent work demonstrates that three widely administered antibiotics (ciprofloxacin, lincomycin, and trimethoprim) are oxidized by potassium permanganate [KMnO(4), Mn(VII)] under conditions relevant to water treatment operations. However, tests show that little to no mineralization occurs during reactions with Mn(VII), so studies were undertaken to characterize the reaction products and pathways and to assess the effects of Mn(VII)-mediated transformations on the antibacterial activity of solutions. Several oxidation products were identified for each antibiotic by liquid chromatography-tandem mass spectrometry (LC-MS/MS). For ciprofloxacin, 12 products were identified, consistent with oxidation of the tertiary aromatic and secondary aliphatic amine groups on the piperazine ring and the cyclopropyl group. For lincomycin, seven products were identified that indicate structural changes to the pyrrolidine ring and thioether group. For trimethoprim, seven products were identified, consistent with Mn(VII) reaction at C═C double bonds on the pyrimidine ring and the bridging methylene group. Oxidation pathways are proposed based on the identified products. Bacterial growth inhibition bioassays (E. coli DH5α) show that the mixture of products resulting from Mn(VII) reactions with the antibiotics collectively retain negligible antibacterial potency in comparison to the parent antibiotics. These results suggest that permanganate can be an effective reagent for eliminating the pharmaceutical activity of selected micropollutants during drinking water treatment.
authors.affiliation: Department of Civil & Environmental Engineering and Center of Advanced Materials for the Purification of Water with Systems, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States. lanhuahu@gmail.com
authors.forename: Lanhua
authors.initials: L
authors.lastname: Hu
authors.forename: Amanda M
authors.initials: AM
authors.lastname: Stemig
authors.forename: Kristine H
authors.initials: KH
authors.lastname: Wammer
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Strathmann
mesh_terms: D000900:Anti-Bacterial Agents / Q000032:analysis / Q000737:chemistry* / Q000633:toxicity; D001681:Biological Assay; D002939:Ciprofloxacin / Q000032:analysis / Q000737:chemistry; D004926:Escherichia coli / Q000187:drug effects; D008034:Lincomycin / Q000737:chemistry; D008345:Manganese / Q000737:chemistry; D010084:Oxidation-Reduction; D011196:Potassium Permanganate / Q000737:chemistry*; D014295:Trimethoprim / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000737:chemistry* / Q000633:toxicity; D018508:Water Purification / Q000379:methods*; D014881:Water Supply / Q000032:analysis
chemical_list: D000900:Anti-Bacterial Agents; D014874:Water Pollutants, Chemical; D011196:Potassium Permanganate; D008345:Manganese; D002939:Ciprofloxacin; D014295:Trimethoprim; D008034:Lincomycin