title: Formation and decomposition of new and unknown polar brominated disinfection byproducts during chlorination.
abstract: Brominated disinfection byproducts (Br-DBPs) are generally more cytotoxic and genotoxic than their chlorinated analogues. A great portion of total organic bromine in chlorinated drinking water is still unknown and may be ascribed to polar Br-DBPs. In this work, a novel approach, precursor ion scan using ultra-performance liquid chromatography/electrospray ionization-triple quadrupole mass spectrometry, was adopted and further developed for selective detection and identification of polar Br-DBPs, which made it possible to reveal the whole picture of the formation and decomposition of polar Br-DBPs during chlorination. Simulated drinking water samples with chlorine contact times from 1 min to 7 d were analyzed. Many new polar aromatic and unsaturated aliphatic Br-DBPs were detected and tentatively proposed with chemical structures, of which 2,4,6-tribromophenol, 3,5-dibromo-4-hydroxybenzoic acid, 2,6-dibromo-1,4-hydroquinone, and 3,3-dibromopropenoic acid were confirmed or identified with authentic standards. It was found that various polar Br-DBPs formed and reached the maximum levels at different chlorine contact times; high molecular weight Br-DBPs might undergo decomposition to relatively low molecular weight Br-DBPs or even finally to haloacetic acids and trihalomethanes. The decomposition of newly detected intermediate Br-DBPs (including molecular ion cluster m/z 345/347/349/351, 2,4,6-tribromophenol, and 3,5-dibromo-4-hydroxybenzoic acid) during chlorination was investigated in detail. The "black box" from the input of "humic substances + bromide + chlorine" through the output of "haloacetic acids + trihalomethanes" was opened to a significant extent.
authors.affiliation: Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, China.
authors.forename: Hongyan
authors.initials: H
authors.lastname: Zhai
authors.forename: Xiangru
authors.initials: X
authors.lastname: Zhang
mesh_terms: D017605:Bromine Compounds / Q000032:analysis* / Q000737:chemistry; D004202:Disinfectants / Q000032:analysis* / Q000737:chemistry; D054879:Halogenation; D006812:Humic Substances / Q000032:analysis; D021241:Spectrometry, Mass, Electrospray Ionization; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000737:chemistry; D018508:Water Purification; D014881:Water Supply / Q000032:analysis
chemical_list: D017605:Bromine Compounds; D004202:Disinfectants; D006812:Humic Substances; D014874:Water Pollutants, Chemical