Development and Application of a High-Precision Algorithm for Nontarget Identification of Organohalogens Based on Ultrahigh-Resolution Mass Spectrometry
Development and Application of a High-Precision Algorithm for Nontarget Identification of Organohalogens Based on Ultrahigh-Resolution Mass Spectrometry
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DOI：
10.1021/acs.analchem.0c02899
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发表时间：
2020-10-20
影响因子：
7.4
通讯作者：
Kwon, Eunsang
中科院分区：
文献类型：
--
作者：
Fu, Qing-Long;Fujii, Manabu;Kwon, Eunsang
在自然和工程环境中经常检测到溴化和/或氯化有机化合物（称为有机卤素）。然而，基于超高分辨率质谱（UHR-MS）的有机卤素非靶向鉴定仍然具有挑战性，因为大量卤化和非卤化有机分子共存。本文提出了一种新的算法，即NOMDBP代码，用于同时从天然水和工程水的UHR-MS光谱中识别有机卤素和非有机卤素。除了同位素模式外，我们还首次将三个可选过滤规则（即选择最小非氧杂原子，检查新形成的卤化消毒副产物（Xn-DBPs）及其前体的存在）纳入我们的代码中，这可以准确识别dbp相关峰，并进一步阐明Xn-DBP的生成和转化机制。与已有报道的2815种有机卤素及其11583种同位素的公式分配比超过97%。将该算法应用于消毒后的天然有机物，结果表明含氧的Xn-DBP物种占Xn-DBP的大多数。此外，溴化Xn-DBPs （Br-DBPs）与氯化Xn-DBPs相比具有更高的不饱和程度。除了亲电取代和亲电加成反应外，分解转化途径是Br-DBP形成的另一个重要机制。这项研究的结果突出了我们的代码在以非靶向方式有效检测未知有机卤素（包括含非氧杂原子的有机卤素）以及识别消毒过程中发生的生成机制方面的优越潜力。
Brominated and/or chlorinated organic compounds (referred to as organohalogens) are frequently detected in natural and engineered environments. However, ultrahigh-resolution mass spectrometry (UHR-MS)-based nontargeted identification of organohalogens remains challenging because of the coexistence of a vast number of halogenated and nonhalogenated organic molecules. In this study, a new algorithm, namely, the NOMDBP code, was developed to simultaneously identify organohalogens and non-organohalogens from the UHR-MS spectra of natural and engineered waters. In addition to isotopic patterns, for the first time, three optional filter rules [i.e., selection for minimum nonoxygen heteroatoms, inspection of the presence of newly formed halogenated disinfection byproducts (Xn-DBPs), and of their precursors] were incorporated into our code, which can accurately identify DBP-associated peaks and further elucidate Xn-DBP generation and transformation mechanisms. The formula assignment ratio against 2815 previously reported organohalogens, and their 11,583 isotopologues exceeded 97%. Application of our algorithm to disinfected natural organic matter indicated that oxygen-containing Xn-DBP species accounted for a majority of the Xn-DBPs. Furthermore, brominated Xn-DBPs (Br-DBPs) were characterized by a higher degree of unsaturation compared to chlorinated Xn-DBPs. In addition to electrophilic substitution and electrophilic addition reactions, the decomposition/ transformation pathway was found to be another important mechanism in Br-DBP formation. The results of this study highlight the superior potential of our code for the efficient detection of yet unknown organohalogens (including organohalogens bearing nonoxygen heteroatoms) in a nontargeted manner and for the identification of their generation mechanism occurring during the disinfection process.