황민욱 (POSTECH)

황민욱 (POSTECH)

서종철 (POSTECH)

황민욱 (POSTECH)

서종철 (POSTECH)

Ion mobility spectrometry (IMS) is a powerful technique used to separate and identify gaseous ions based on their overall shape. However, conventional drift tube ion mobility spectrometry (DTIMS) faces limitations in resolving power due to practical constraints such as the high voltage requirement and the need for a large space to accommodate the long, linear drift tube. To overcome these challenges, traveling wave ion mobility spectrometry (TWIMS), which employs dynamic square waves to move ions through a buffer gas, has gained attention as a more effective method for ion mobility separation. In this study, we developed a custom-built traveling wave ion mobility spectrometer, coupled with a time-of-flight (TOF) mass spectrometer. The IMS modules were constructed from printed circuit boards (PCBs) containing a series of electrodes that guide and move ions along a well-defined path between the two boards. (Structures for Lossless Ion Manipulations, SLIM). Two linear modules, each approximately 303 mm in length, were arranged to create a total separation distance of 606 mm. The operation of the overall instrument is as follows: 1) A nanoelectrospray assembly generates charged nanodroplets at ambient pressure; 2) These nanodroplets enter the first vacuum chamber through an 87 mm long, 508 μm i.d. inlet capillary and are briefly trapped in an ion trap funnel; 3) The ions are then ejected from the funnel and transferred to the IMS chamber; 4) The ions are separated by traveling waves in a buffer gas environment of 4–5 mbar; 5) The ions pass through a differential pumping region using ion guides such as cylindrical stacked ring guides or multipole ion guides; 6) The ions are either detected by an ion mobility detector or deflected orthogonally by high voltage pulses to reach a TOF detector in a high vacuum region; 7) The detected ion current signals are first amplified in a preamplifier, then further amplified and converted from current to voltage by an amplifier; 8) The voltage signals are then converted to ion intensity and stored in memory by an analog-to-digital converter (ADC).

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