首页> 外文期刊>Journal of mass spectrometry: JMS >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
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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

机译:在飞行时间质谱中高离子通量引起的微通道板增益降低的评价:一种使用多匝飞行时间质谱仪的新型评价方法

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摘要

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 ( increment 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 mu s for channel plate resistances of 500 and 71 M omega, respectively. The obtained time constants from the gains determined at various values of increment t were 0.48 and 0.38 fold (for 500 and 71 M omega, respectively) of the values suggested from the channel plate resistance and capacitance.
机译:两级微通道板(MCP)检测器在飞行时间(TOF)质谱分析中很常见,因为它具有良好的时间分辨率和足够的增益。然而,当探测器通过基质辅助激光解吸/电离质谱检测到强烈的离子通量(如基质离子)时,增益显著下降。因此,与蛋白质等分析物相对应的重要离子信号被隐藏,从而妨碍质谱解释。然而,由于缺乏合适的测量方法和仪器,这种现象的细节之前没有使用离子进行研究。因此,我们在此报告了一种新的方法,用于控制两个选定离子的TOF,作为使用多圈TOF质谱仪的时间差的函数。这种方法包括使用一个同位素离子簇,这些离子以八字形轨道飞行,并提取给定圈数的离子。使用这种方法可以在TOF光谱中产生两个离子之间的一系列时间差(增量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500和71 MΩ通道板电阻分别为1600和180μs的值。从在不同增量t值下确定的增益中获得的时间常数是通道板电阻和电容建议值的0.48倍和0.38倍(分别适用于500和71 MΩ)。

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