Ion-mobility spectrometry–mass spectrometry
Ion mobility spectrometry–mass spectrometry (IMS-MS) is an analytical chemistry method that separates gas phase ions based on their interaction with a collision gas and their masses. In the first step, the ions are separated according to their mobility through a buffer gas on a millisecond timescale using an ion mobility spectrometer.
Source: Wikipedia — Ion-mobility spectrometry–mass spectrometry (CC BY-SA 4.0)