Abstract: A mass spectrometry method comprises generating ions and separating the ions in an ion mobility cell. Some of the generated ions can be contacted with a mobility modifier. The ions can be analyzed with a mass analyzer.

Abstract: A method of dissociating ions in a multipole ion guide is disclosed. A stream of charged ions is supplied to the ion guide. A main RF field is applied to the ion guide to confine the ions through the ion guide. An excitation RF field is applied to one pair of rods of the ion guide. The ions undergo dissociation when the applied excitation RF field is resonant with a secular frequency of the ions. The multipole ion guide is, but not limited to, a quadrupole, a hexapole, and an octopole.

Abstract: A method of operating a quadrupole mass spectrometer is described where one of the stages thereof has a pairs of opposing rods and one of the pair of rods is operated with a zero voltage potential difference therebetween and the other of the pair of opposing rods is operated with a voltage potential difference therebetween. The potential field unbalance causes the analyte ions to deviate from the axial centerline of the stage so as to undergo additional RF heating. The stage is operated in a transmission mode and the resultant reaction products may be further processed in subsequent stages or output to a mass spectrometer.