Ontario Ministry of the Environment, Toronto, ON, Canada.
Anal Bioanal Chem. 2013 Apr;405(10):3289-97. doi: 10.1007/s00216-013-6735-2. Epub 2013 Jan 27.
Mass defect is the difference between the nominal and exact mass of a chemical element or compound. An intrinsic property of polyhalogenated molecules is a uniquely negative mass defect, which readily distinguishes halogenated from non-halogenated compounds in a complex mass spectrum and can be visualized by constructing a mass defect plot. This study demonstrates the utility of the mass defect plot as a powerful tool to screen gas-chromatography (ultra)high-resolution mass spectrometry data for potentially toxic and bioaccumulative halogenated compounds in a Lake Ontario lake trout, an apex species in the Great Lakes environment. Our results indicate that the sample is contaminated with polychlorinated biphenyls, terphenyls, diphenylethers, as well as other chlorinated pesticides and flame retardants that are regulated and routinely analyzed by traditional target analyses. However, the mass defect plot also displays peaks which could be traced to the presence of as yet undiscovered contaminants. These include chlorinated polycyclic aromatic hydrocarbons as well as mixed halogenated analogues of the flame retardant Dechlorane 604. The identity of the latter class of compounds is supported by experiments with genuine standards.
质量亏损是指化学元素或化合物的名义质量与实际质量之间的差异。多卤代分子的一个固有特性是独特的负质量亏损，这在复杂的质谱中很容易将卤代化合物与非卤代化合物区分开来，并可以通过构建质量亏损图来可视化。本研究证明了质量亏损图作为一种强大工具的实用性，可用于筛选安大略湖湖鳟鱼（大湖环境中的顶级物种）中气相色谱（超高分辨率）质谱数据中潜在有毒和生物累积的卤代化合物。我们的结果表明，该样品受到多氯联苯、三联苯、二苯醚以及其他受管制和常规进行传统目标分析的氯化农药和阻燃剂的污染。然而，质量亏损图也显示出可能是尚未发现的污染物存在的峰。这些包括氯化多环芳烃以及阻燃剂 Dechlorane 604 的混合卤代类似物。后一类化合物的身份得到了真实标准品实验的支持。
