Tandem mass spectrometry (MS/MS) is often used to identify lipids in matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI IMS) workflows. The molecular specificity afforded by MS/MS is crucial on MALDI time-of-flight (TOF) platforms that generally lack high resolution accurate mass measurement capabilities. Unfortunately, imaging MS/MS workflows generally only monitor a single precursor ion over the imaged area, limiting the throughput of this methodology. Herein, we demonstrate that multiple TOF/TOF events performed in each laser shot can be used to improve the throughput of imaging MS/MS. This is shown to enable the simultaneous identification of multiple phosphatidylcholine lipids in rat brain tissue. Uniquely, the separation in time achieved for the precursor ions in the TOF-1 region of the instrument is maintained for the fragment ions as they are analyzed in TOF-2, allowing for the differentiation of fragment ions of the exact same m/z derived from different precursor ions (e.g., the m/z 163 fragment ion from precursor ion m/z 772.5 is easily distinguished from the m/z 163 fragment ion from precursor ion m/z 826.5). This multiplexed imaging MS/MS approach allows for the acquisition of complete fragment ion spectra for multiple precursor ions per laser shot.

中文翻译：

---

用于 MALDI 成像质谱中多重脂质识别的单次激光射击中的多个 TOF/TOF 事件

串联质谱 (MS/MS) 通常用于在基质辅助激光解吸/电离成像质谱 (MALDI IMS) 工作流程中识别脂质。MS/MS 提供的分子特异性对于通常缺乏高分辨率精确质量测量能力的 MALDI 飞行时间 (TOF) 平台至关重要。不幸的是，成像 MS/MS 工作流程通常仅监测成像区域上的单个母离子，限制了该方法的通量。在此，我们证明在每次激光发射中执行的多个 TOF/TOF 事件可用于提高成像 MS/MS 的吞吐量。这表明能够同时识别大鼠脑组织中的多种磷脂酰胆碱脂质。独一无二，在 TOF-2 中分析碎片离子时，仪器 TOF-1 区域中母离子实现的时间分离保持不变，从而可以区分来自不同来源的完全相同 m/z 的碎片离子母离子（例如，来自母离子 m/z 772.5 的 m/z 163 碎片离子很容易与来自母离子 m/z 826.5 的 m/z 163 碎片离子区分开来）。这种多路复用成像 MS/MS 方法允许为每次激光发射获取多个母离子的完整碎片离子谱。5）。这种多路复用成像 MS/MS 方法允许为每次激光发射获取多个母离子的完整碎片离子谱。5）。这种多路复用成像 MS/MS 方法允许为每次激光发射获取多个母离子的完整碎片离子谱。