title: UV-induced transformation of four halobenzoquinones in drinking water.
abstract: Halobenzoquinones (HBQs) are a group of emerging disinfection byproducts (DBPs) found in treated drinking water. Because the use of UV treatment for disinfection is becoming more widespread, it is important to understand how the HBQs may be removed or changed due to UV irradiation. Water samples containing four HBQs, 2,6-dichloro-1,4-benzoquinone (DCBQ), 2,3,6-trichloro-1,4-benzoquinone (TCBQ), 2,6-dichloro-3-methyl-1,4-benzoquinone (DCMBQ), and 2,6-dichloro-1,4-benzoquinone (DBBQ), were treated using a modified bench scale collimated beam device, mimicking UV treatment. Water samples before and after UV irradiation were analyzed for the parent compounds and products using a high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) method. As much as 90% of HBQs (0.25 nmol L(-1)) in both pure water and tap water were transformed to other products after UV254 irradiation at 1000 mJ cm(-2). The major products of the four HBQs were identified as 3-hydroxyl-2,6-dichloro-1,4-benzoquinone (OH-DCBQ) from DCBQ, 5-hydroxyl-2,6-dichloro-3-methyl-1,4-benzoquinone (OH-DCMBQ) from DCMBQ, 5-hydroxyl-2,3,6-trichloro-1,4-benzoquinone (OH-TCBQ) from TCBQ, and 3-hydroxyl-2,6-dibromo-1,4-benzoquinone (OH-DBBQ) from DBBQ. These four OH-HBQs were further modified to monohalogenated benzoquinones when the UV dose was higher than 200 mJ cm(-2). These results suggested possible pathways of UV-induced transformation of HBQs to other compounds. Under the UV dose commonly used in water treatment plants, it is likely that HBQs are partially converted to other halo-DBPs. The occurrence and toxicity of these mixed DBPs warrant further investigation to understand whether they pose a health risk.
authors.affiliation: Division of Analytical and Environmental Toxicology, Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, Alberta, Canada, T6G 2G3.
authors.forename: Yichao
authors.initials: Y
authors.lastname: Qian
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.forename: Jessica M
authors.initials: JM
authors.lastname: Boyd
authors.forename: Minghuo
authors.initials: M
authors.lastname: Wu
authors.forename: Steve E
authors.initials: SE
authors.lastname: Hrudey
authors.forename: Xing-Fang
authors.initials: XF
authors.lastname: Li
mesh_terms: D016227:Benzoquinones / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D060766:Drinking Water / Q000737:chemistry*; D006219:Halogens / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet; D053719:Tandem Mass Spectrometry; D014466:Ultraviolet Rays
chemical_list: D016227:Benzoquinones; D060766:Drinking Water; D006219:Halogens