Department of Chemistry, Center for Innovative Technology, Vanderbilt Institute of Chemical Biology, Vanderbilt Institute for Integrative Biosystems Research and Education, Vanderbilt University , Nashville, Tennessee 37235, United States.
Intel Corporation , Hillsboro, Oregon 97124, United States.
Anal Chem. 2018 Feb 6;90(3):1915-1924. doi: 10.1021/acs.analchem.7b04007. Epub 2018 Jan 17.
The increasing focus on lipid metabolism has revealed a need for analytical techniques capable of structurally characterizing lipids with a high degree of specificity. Lipids can exist as any one of a large number of double bond positional isomers, which are indistinguishable by single-stage mass spectrometry alone. Ozonolysis reactions coupled to mass spectrometry have previously been demonstrated as a means for localizing double bonds in unsaturated lipids. Here we describe an online, solution-phase reactor using ozone produced via a low-pressure mercury lamp, which generates aldehyde products diagnostic of cleavage at a particular double bond position. This flow-cell device is utilized in conjunction with structurally selective ion mobility-mass spectrometry. The lamp-mediated reaction was found to be effective for multiple lipid species in both positive and negative ionization modes, and the conversion efficiency from precursor to product ions was tunable across a wide range (20-95%) by varying the flow rate through the ozonolysis device. Ion mobility separation of the ozonolysis products generated additional structural information and revealed the presence of saturated species in a complex mixture. The method presented here is simple, robust, and readily coupled to existing instrument platforms with minimal modifications necessary. For these reasons, application to standard lipidomic workflows is possible and aids in more comprehensive structural characterization of a myriad of lipid species.
对脂质代谢的日益关注揭示了对能够高度特异性地对脂质进行结构特征分析的分析技术的需求。脂质可以作为大量双键位置异构体中的任何一种存在，仅凭单阶段质谱法无法区分这些异构体。臭氧氧化反应与质谱法的结合已被证明是定位不饱和脂质中双键的一种手段。在这里，我们描述了一种在线溶液相反应器，使用通过低压汞灯产生的臭氧，生成醛产物，可用于诊断特定双键位置的断裂。该流动池装置与结构选择性离子淌度-质谱联用。该灯介导的反应在正离子和负离子模式下对多种脂质物质均有效，并且通过改变臭氧分解装置中的流速，可以在很宽的范围内（20-95%）调节从前体到产物离子的转换效率。臭氧分解产物的离子淌度分离提供了额外的结构信息，并揭示了在复杂混合物中存在饱和物质。这里提出的方法简单、稳健，并且可以轻松与现有的仪器平台结合，无需进行大量修改。由于这些原因，该方法可应用于标准脂质组学工作流程，并有助于对众多脂质物质进行更全面的结构特征分析。
