Fourier Transform-Ion Mobility Linear Ion Trap Mass Spectrometer Using Frequency Encoding for Recognition of Related Compounds in a Single Acquisition.

Fourier transform-ion mobility spectrometry is implemented by coupling a 3D-printed drift tube ion mobility spectrometer, operated at atmospheric pressure, to a linear ion trap mass spectrometer. FT-IMS separations are demonstrated for tetraalkylammonium salts, explosives, fentanyls, and amphetamines. Mobility resolving powers of up to 17 are measured for the tetraalkylammonium cations. When ions are fragmented in the FT-IMS mode, the product ions maintain the frequency and amplitude relationships established during the mobility measurement. Therefore, precursors and product ion relationships can be identified through the mobility information. Using in-source activation for nonspecific fragmentation of all precursors, functional group families of precursors and product ions are identified in a single acquisition. The identity of the precursor ion is not known a priori, but the m/z values for both precursors and product ions are measured.