Particular aspects provide novel methods for analysis of ion populations,
the methods comprising filtering and selecting an ion population using a
low-field dual-gate ion mobility spectrometer comprising a drift tube,
the spectrometer operating at a pressure of at least 100 Torr, to provide
mobility-selected ions. Certain aspects comprise: (i) subsequently
accumulating the low-field selected ions in an ion trap (e.g., an MS ion
trap) and mass spectrometry analysis; (ii) introducing the low-field
selected ions into a high-field ion mobility spectrometer for separating
thereby (optionally followed by mass spectrometry); and (iii) introducing
the low-field selected ions into an ion trap mass spectrometer, and
subsequently into a second low-field ion mobility spectrometer (e.g., a
non-dual gate spectrometer operating at less than about 100 Torr).
Additional aspects provide novel apparatus and combination thereof for
performing the disclosed methods.