title: Ozonation of trimethoprim in aqueous solution: identification of reaction products and their toxicity.
abstract: This work aimed to better understand the ozonation process of a typical antibiotic pharmaceutical, trimethoprim in aqueous solution. The parent compound was almost completely degraded with ozone dose up to 3.5 mg/L with no mineralization. Twenty one degradation products were identified using an electrospray quadrupole time-of-flight mass spectrometer. Several ozonation pathways were proposed including hydroxylation, demethylation, carbonylation, deamination and methylene group cleavage. Two species of luminescent bacteria Photobacterium phosphoreum and Vibrio qinghaiensis were selected to assess the toxicity of ozonation products. For P. phosphoreum, higher level of toxicity was observed compared to the parent compound, but a negligible toxicity change was observed for V. qinghaiensis, indicating different modes of action for the same water sample. This was further confirmed by quantitative structure-active relationship analysis. This work proves the dominant role of ozone rather than hydroxyl radicals in the reaction and the potential risk after ozonation.
authors.affiliation: State Key Joint Laboratory of Environmental Simulation and Pollution Control (SKJLESPC), School of Environment, Tsinghua University, Beijing 100084, China.
authors.forename: Jiangmeng
authors.initials: J
authors.lastname: Kuang
authors.forename: Jun
authors.initials: J
authors.lastname: Huang
authors.forename: Bin
authors.initials: B
authors.lastname: Wang
authors.forename: Qiming
authors.initials: Q
authors.lastname: Cao
authors.forename: Shubo
authors.initials: S
authors.lastname: Deng
authors.forename: Gang
authors.initials: G
authors.lastname: Yu
mesh_terms: D000890:Anti-Infective Agents / Q000032:analysis / Q000737:chemistry / Q000633:toxicity; D002851:Chromatography, High Pressure Liquid; D010126:Ozone / Q000737:chemistry*; D010776:Photobacterium / Q000187:drug effects*; D021281:Quantitative Structure-Activity Relationship; D021241:Spectrometry, Mass, Electrospray Ionization; D053719:Tandem Mass Spectrometry; D014295:Trimethoprim / Q000032:analysis / Q000737:chemistry / Q000633:toxicity*; D014733:Vibrio / Q000187:drug effects*; D014865:Waste Disposal, Fluid; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000737:chemistry / Q000633:toxicity*
chemical_list: D000890:Anti-Infective Agents; D014874:Water Pollutants, Chemical; D010126:Ozone; D014295:Trimethoprim