A new charge detection mass spectrometer that combines array detection and electrostatic ion trapping to repeatedly measure the masses of single ions is described. This instrument has four detector tubes inside an electrostatic ion trap with conical electrodes (cone trap) to provide multiple measurements of an ion on each pass through the trap resulting in a signal gain over a conventional trap with a single detection tube. Simulations of a cone trap and a dual ion mirror trap design indicate that more passes through the trap per unit time are possible with the latter. However, the cone trap has the advantages that ions entering up to 2 mm off the central axis of the trap are still trapped, the trapping time is less sensitive to the background pressure, and only a narrow range of energies are trapped so it can be used for energy selection. The capability of this instrument to obtain information about the molecular weight distributions of heterogeneous high molecular weight samples is demonstrated with 8 MDa polyethylene glycol (PEG) and 50 and 100 nm amine modified polystyrene nanoparticle samples. The measured mass distribution of the PEG sample is centered at 8 MDa. The size distribution obtained from mass measurements of the 100 nm nanoparticle sample is similar to the size distribution obtained from transmission electron microscopy (TEM) images, but most of the smaller nanoparticles observed in TEM images of the 50 nm nanoparticles do not reach a sufficiently high charge to trigger the trap on a single pass and be detected by the mass spectrometer. With the maximum trapping time set to 100 ms, the charge uncertainty is as low as ±2 charges and the mass uncertainty is approximately 2% for PEG and polystyrene ions.

中文翻译：

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单粒子质量分析仪：带多检测器静电离子阱的电荷检测质谱仪

描述了一种新的电荷检测质谱仪，它结合了阵列检测和静电离子捕获来重复测量单个离子的质量。该仪器在带有锥形电极（锥形阱）的静电离子阱内有四个检测管，可在每次通过离子阱时对离子进行多次测量，从而产生比具有单个检测管的传统阱的信号增益。锥形阱和双离子镜阱设计的模拟表明，后者每单位时间通过阱的次数可能更多。然而，锥形阱的优点是进入离阱中心轴 2 mm 以内的离子仍然被捕获，捕获时间对背景压力不太敏感，并且只捕获窄范围的能量，因此它可以被用于能量选择。8 MDa 聚乙二醇 (PEG) 和 50 和 100 nm 胺改性聚苯乙烯纳米颗粒样品证明了该仪器能够获取有关异质高分子量样品的分子量分布信息。PEG 样品的测量质量分布集中在 8 MDa。从 100 nm 纳米颗粒样品的质量测量中获得的尺寸分布类似于从透射电子显微镜 (TEM) 图像中获得的尺寸分布，但在 50 nm 纳米颗粒的 TEM 图像中观察到的大多数较小的纳米颗粒没有达到足够高的充电以在单次通过时触发陷阱并被质谱仪检测到。将最大捕获时间设置为 100 ms，