Polyhalogenated Carbazoles in Sediments of Lake Michigan: A New Discovery

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• 作者：Jiehong Guo ; Da Chen ; Dave Potter ; Karl J. Rockne ; Neil C. Sturchio ; John P. Giesy ; An Li
• 刊名：Environmental Science & Technology
• 出版年：2014
• 出版时间：November 4, 2014
• 年：2014
• 卷：48
• 期：21
• 页码：12807-12815
• 全文大小：507K
• ISSN：1520-5851

文摘

Previously unknown halogenated compounds were detected during the analysis of halogenated flame retardants in two sediment cores collected from Lake Michigan. Gas chromatography coupled with high- or low-resolution mass spectrometry (MS) was used to determine the chemical structures for a total of 15 novel polyhalogenated carbazoles (PHCs) with the general molecular formula C₁₂H_9-x-y-zNCl_xBr_yI_z. On the basis of the mass spectra generated by electron impact (EI) and electron capture negative ionization (ECNI) MS, eight PHCs were tentatively identified as polybrominated carbazoles, while the others were mixed halogenated carbazoles containing, in addition to bromine, either chlorine or iodine or both. Patterns of halogen substitution of PHCs included Br₂ to Br₅, ClBr₂, ClBr₃, ClBr₄, ClBr₃I, Br₄I, and Br₃I₂. 3,6-Dibromocarbazole and 1,3,6,8-tetrabromocarbazole were also found among the PHCs. Profiles of the concentration versus depth of sediment at the two sites showed various patterns among polybrominated carbazoles. The abundance of mixed halogenated carbazoles peaked at depths of 12鈥?6 cm, remained at relatively constant levels in deeper sediment, but declined markedly in more recently deposited sediments. This is the first study discovering the seven mixed halogenated carbazoles in the environment. Detailed methods for their detection and identification are provided.