Evaluation of microchannel plate gain drops caused by high ion fluxes in time‐of‐flight mass spectrometry: A novel evaluation method using a multi‐turn time‐of‐flight mass spectrometer
Evaluation of microchannel plate gain drops caused by high ion fluxes in time‐of‐flight mass spectrometry: A novel evaluation method using a multi‐turn time‐of‐flight mass spectrometer
复制标题
评估飞行时间质谱中高离子通量引起的微通道板增益下降：一种使用多转飞行时间质谱仪的新型评估方法
DOI：
10.1002/jms.4706
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发表时间：
2021
影响因子：
2.3
通讯作者：
Michisato Toyoda
中科院分区：
文献类型：
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作者：
Hiroshi Kobayashi;Toshinobu Hondo;Michisato Toyoda
两级微通道板（MCP）检测器在飞行时间（TOF）质谱中很常见，因为它具有良好的时间分辨率和足够的增益。然而，当检测器通过基质辅助激光解吸/电离质谱法检测强离子通量（例如基质离子）时，增益显著下降。结果，对应于分析物（例如蛋白质）的显著离子信号被隐藏，从而妨碍质谱解释。然而，由于缺乏合适的测量方法和设备，这种现象的细节以前没有使用离子进行研究。因此，我们在本文中报告了一种用于控制两个选定离子的TOF的新方法，作为使用多圈TOF质谱仪的彼此之间的时间差的函数。这种方法涉及使用在8字形轨道上飞行的同位素离子簇，并在给定的圈数下提取离子。使用这种方法可以在TOF谱中产生两个离子之间的一系列时间差（Δ t）。我们评估了两组两级MCP探测器在高离子通量检测后的增益恢复时间常数，以获得通道板电阻为500和71 MΩ时分别为1，600和180 μs的值。在不同的增益下测得的时间常数分别是通道板电阻和电容值的0.48和0.38倍（分别为500和71 MΩ）。
Use of a two‐stage microchannel plate (MCP) detector is common in time‐of‐flight (TOF) mass spectrometry because it shows excellent time resolution with sufficient gains. However, the gain drops significantly when the detector detects intense ion fluxes, such as matrix ions, by matrix‐assisted laser desorption/ionization mass spectrometry. As a result, significant ion signals corresponding to analytes, such as proteins, are hidden, thereby hampering the mass spectral interpretation. However, details of this phenomenon have not previously been investigated using ions because of the lack of suitable measurement methods and apparatus. Thus, we herein report a novel method for controlling the TOF of two selected ions, as a function of time differences between each other using a multi‐turn TOF mass spectrometer. This method involves the use of an isotope cluster of ions that fly in a figure‐of‐eight orbit and the extraction of an ion at a given lap number. A series of time differences (∆t) between two ions in a TOF spectrum can be generated using this method. We evaluated the time constants of gain recovery after high ion‐flux detection for two sets of two‐stage MCP detectors to obtain values of 1,600 and 180 μs for channel plate resistances of 500 and 71 MΩ, respectively. The obtained time constants from the gains determined at various values of ∆twere 0.48 and 0.38 fold (for 500 and 71 MΩ, respectively) of the values suggested from the channel plate resistance and capacitance.