title: Electrospray ionization-tandem mass spectrometry method for differentiating chlorine substitution in disinfection byproduct formation.
abstract: An electrospray ionization-tandem mass spectrometry (ESI-tqMS) method was developed to identify the location of chlorine substitution during the chlorination of model organic compounds. The chlorine substitution in the aliphatic part and that in the benzene ring of an organic molecule can be differentiated by their corresponding ranges of optimum collision energies, 5-7 eV and over 15 eV, respectively, in the precursor ion scan of m/z 35. The method was applied to predict the structures of intermediates and reveal the transformation pathways during the chlorination of 4-amino-2-chlorobenzoic acid and phenylalanine as a function of reaction time and the chlorine-to-precursor ratio. In the case of phenylalanine, chlorine was found to replace one hydrogen atom attached to the aliphatic nitrogen; in the case of 4-amino-2-chlorobenzoic acid, chlorine was found to replace the hydrogen atoms attached to the aromatic rings.
authors.affiliation: Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology , Clear Water Bay, Kowloon, Hong Kong.
authors.forename: Zhuo
authors.initials: Z
authors.lastname: Deng
authors.forename: Xin
authors.initials: X
authors.lastname: Yang
authors.forename: Chii
authors.initials: C
authors.lastname: Shang
authors.forename: Xiangru
authors.initials: X
authors.lastname: Zhang
mesh_terms: D002713:Chlorine / Q000032:analysis*; D004202:Disinfectants / Q000737:chemistry*; D054879:Halogenation; D007700:Kinetics; D010649:Phenylalanine / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D053719:Tandem Mass Spectrometry / Q000379:methods*; D005680:gamma-Aminobutyric Acid / Q000031:analogs & derivatives / Q000737:chemistry
chemical_list: D004202:Disinfectants; D010649:Phenylalanine; D002713:Chlorine; D005680:gamma-Aminobutyric Acid; C029210:2-chloro-4-aminobenzoic acid