Detection,identification,formation And Occurrence Of New Polar Halogenated Disinfection Byproducts In Drinking Water

During drinking water disinfection,halogenated disinfection byproducts(DBPs)can be generated through reactions by iodide/bromide,disinfectants(chlorine/chloramines),and natural organic matter.A few toxicological studies have showed that halogenated DBPs had high cytotoxicity and genotoxicity.The exposure to halogenated DBPs in drinking water could result in an increased cancer risk.Actually,50%of the DBPs produced in chlorinated drinking water has not been well characterized,and the percentages of unknown DBPs produced in drinking water treated with other disinfectants were even higher.A majority of the unknown DBPs should be polar or highly polar,which is not amenable to detection by commonly used gas chromatography/mass spectrometry(GC/MS).Accordingly,there should be a large number of polar/hydrophilic/non-volatile halogenated DBPs formed in drinking water that has long eluded researchers.In this study,a novel approach-Precursor ion scan using ultra performance liquid chromatography/electrospray ionization-triple quadrupole mass spectrometry(UPLC/ESI-tqMS)-was adopted for the detection of almost all polar iodinated DBPs in drinking water.With the aid of UPLC/ESI-tqMS multiple reaction monitoring and product ion scan,11 new polar iodinated DBPs were confirmed with structures and eight new polar iodinated DBPs were proposed.We further studied factors that may affect the formation of the 19 new polar iodinated DBPs during drinking water disinfection,including the natural organic matter of source water,disinfectant type,and pH.Notably,the occurrence frequencies and levels of these new polar iodinated DBPs were investigated in real tap water samples collected in nine major cities from the Yangtze River Delta region of China.Moreover,we report the detection,synthesis,preparative isolation,structure characterization/identification,and formation of a new group of drinking water DBPs-trihalo-hydroxy-cyclopentene-diones(trihalo-HCDs).With UPLC/ESI-tqMS analyses(full scans,multiple reaction monitoring,and product ion scans)and high resolution mass spectrometry analyses(full scans),the new group of DBPs was identified with formulae and proposed with structures.The new disinfection byproduct with m/z 345/347/349/351(tribromo species in the new group of DBPs)was synthesized using optimized reaction conditions.With UPLC/Photodiode Array analysis(simultaneous 2-and 3-dimensional operations),the new DBP was determined to have a maximum UV absorption at the wavelength of280 nm.Through isolation with high performance liquid chromatography/UV-triggered collections followed by lyophilization,the pure standard of the new DBP was obtained.Characterized with Fourier Transformation Infrared Spectroscopy,the pure standard of the new DBP was finally identified to be tribromo-HCD,and thus the new group of DBPs was identified to be trihalo-HCDs.Based on the disclosed structure,formation pathways of tribromo-HCD through reactions of three different precursors and bromine were elucidated.We further studied factors that may affect the formation of trihalo-HCDs during drinking water disinfection,including source water bromide level,disinfectant type,contact time,and pH.The occurrence frequencies and levels of tribromo-HCD were investigated in real tap water samples collected in eight major cities from the Yangtze River Delta region of China.The successful detection and identification of the new polar iodinated DBPs and trihalo-HCDs provided novel and effective methods for exploring new DBPs in drinking water.The investigation of the formation and occurrence of these new polar halogenated DBPs provided basis for the control of DBPs pollution in drinking water.