Digital asymmetric waveform isolation (DAWI) in a digital linear ion trap.

Traditionally, in a quadrupole mass filter, ion isolation is achieved by scanning the rf and DC voltages with a fixed ratio. In this paper, we describe an innovative procedure implemented in a digitally driven linear ion trap termed digital asymmetric waveform isolation (DAWI) in which ion isolation is obtained by manipulation of the duty cycle of the rectangular waveforms. Variation of the waveform duty cycle allows introduction of a precisely defined DC quadrupole component into the main trapping field of the quadrupole ion filter. The DAWI method is completely controlled at software level and does not require any hardware modification.