Tandem RF-only quadrupole mass filter with quadrupolar excitation

Abstract We report the computer simulation results of a tandem RF-only quadrupole mass filter. This mass filter consists of two short quadrupole rod sets, Q1 and Q2. The first quadrupole, Q1, is operated as a higher mass reject filter to remove lower q ions. The main filter, Q2, is a RF-only quadrupole, and it is used to give suitable narrow pass band on q axis. Quadrupole excitation by additional RF voltage leads to instability bands along q axis between q  = 0 and q  = 0.2, and this instability band can be used to remove low q ions with m  =  M 0  −  ∞ mass range. Quadrupole excitation creates a narrow pass band near q 0  = 0.9080 in Q2. R 0.1  = 1150 could be achieved at short separation time n  = 40 in Q2.