Patent ID: 9552969
Date: 2017-01-24
CPC Classifications: G01N,H01J

Claim:
1. A method of separating ions according to their ion mobility with an RF ion guide having a plurality of electrodes arranged to form an ion guiding path that extends in a closed loop, said method comprising: supplying RF voltages to at least some of said electrodes in order to confine ions within said ion guiding path; and maintaining a DC voltage gradient in a DC voltage gradient region along at least a portion of a longitudinal axis of said ion guide, wherein said voltage gradient urges the ions to undergo one or more cycles around said ion guide and thus causes the ions to separate according to their ion mobility as the ions pass along the ion guide; wherein the DC voltage gradient moves around the ion guide at a rate such that at least some of said ions continually remain within the DC voltage gradient region as the ions travel around the ion guide and until such ions are extracted from the ion guide at an exit region of the ion guide.