Department of Chemistry, Washington State University, Pullman, Washington.
J Mass Spectrom. 2020 Jun;55(6):e4510. doi: 10.1002/jms.4510. Epub 2020 Mar 12.
The acceptance of quadrupole mass filters is improved when the alternating current (AC) and direct current (DC) fields are developed separately. Physically, this is achieved when a short RF only quadrupole (prefilter) is situated directly ahead of the mass filter. The acceptance gained by a system operating with a prefilter can be observed as an increase in sensitivity over conventional operation. Frequency dynamic duty cycle based rectangular waveform driven (rectangular wave) mass filters, a recent development, currently do not operate with prefilters. Little is known about the influence of duty cycle changes on the acceptance of rectangular wave mass filters. The sensitivity gain seen by conventional systems operating with prefilters indicates that the sensitivity of duty cycle based rectangular wave systems should increase comparably. The objective of this work was to determine prefilter efficacy for nonspecific rectangular wave mass filter systems. In this work, the plane method of acceptance was used to model the change to the acceptance and transmittance of sine and rectangular waveform driven mass filters under different modes of field development. Both systems indicated a fourfold increase in sensitivity when the mass filtering DC or duty cycle was delayed.
当分别开发交流 (AC) 和直流 (DC) 场时，四极质量滤波器的接受率会提高。从物理上讲，当短射频仅四极 (预滤波器) 直接位于质量滤波器之前时，就可以实现这一点。具有预滤波器的系统的接受率可以观察到灵敏度相对于传统操作的提高。最近开发的基于频率动态占空比的矩形波驱动 (矩形波) 质量滤波器目前不能与预滤波器一起使用。对于占空比变化对矩形波质量滤波器的接受率的影响知之甚少。带有预滤波器的传统系统所看到的灵敏度增益表明，基于占空比的矩形波系统的灵敏度应该相应提高。这项工作的目的是确定非特定矩形波质量滤波器系统的预滤波器功效。在这项工作中，采用平面接受法对正弦和矩形波驱动质量滤波器在不同场开发模式下的接受率和传输率的变化进行建模。当质量滤波的 DC 或占空比延迟时，两个系统的灵敏度都增加了四倍。
