Because of the difficulty of carbon–carbon bond cleavage needed to liberate the small molecule chlorine disinfection byproducts (DBPs; e.g., trihalomethanes), they typically form at <1% yields. By using N-acetyl-tryptophan (NacTrp) as a model reactive peptide-bound monomer within natural organic matter (NOM), this study illustrates the characterization of its initial chlorine transformation products as an alternative approach to identify high-yield DBPs. When NacTrp was treated at 1–10 chlorine/NacTrp molar ratios, seven novel initial transformation products were purified and characterized by high-resolution mass spectrometry, including two chlorine-containing DBPs. The total concentrations of these novel DBPs accounted for 55–100% conversion of the parent NacTrp at 1–5 chlorine/NacTrp molar ratios over 24 h, compared to ≤5% for the total concentrations of small molecule DBPs. At a 10:1 molar ratio, the novel DBP concentrations declined over 24 h to account for 25% molar conversion, while small molecule DBP concentrations increased, yet still accounted for only 20% molar conversion. A reaction pathway consistent with these initial transformation products was proposed. The high yields of these novel DBPs are attributable to the lack of carbon–carbon bond cleavage. This study illustrates the identification of initial transformation products of important monomers as an efficient option to characterize the unknown DBPs.

中文翻译：

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色氨酸的新型氯化副产物：最初的高产转化产物与小分子消毒副产物

由于释放小分子氯消毒副产物（DBP；例如三卤甲烷）所需的碳-碳键断裂困难，它们的形成产率通常<1％。通过使用N-乙酰基色氨酸（NacTrp）作为天然有机物（NOM）中的模型反应性肽结合单体，该研究说明了其初始氯转化产物的表征，作为鉴定高产率DBP的替代方法。当NacTrp以1-10氯/ NacTrp摩尔比处理时，纯化了七个新颖的初始转化产物，并通过高分辨率质谱进行了表征，包括两个含氯的DBP。这些新颖的DBP的总浓度占24小时内1-5氯/ NacTrp摩尔比下母体NacTrp的55-100％的转化，而小分子DBP的总浓度≤5％。摩尔比为10：1时，新的DBP浓度在24小时内下降，占25％的摩尔转化率，而小分子DBP浓度增加，但仍仅占20％的摩尔转化率。提出了与这些初始转化产物一致的反应途径。这些新型DBP的高产量归因于碳-碳键断裂的缺乏。这项研究说明了重要单体的初始转化产物的鉴定是表征未知DBP的有效选择。