Waveboard artifacts generate ghost resonances consistent with equations for predicting ion motion in commercial quadrupole ion traps

Real-time experiments involving fragmentation of the precursor molecular ion of n-butylbenzene (m/z 134) to produce product ions C₇H ⁺₇, (m/z 91) and C₇H⁺₈ (m/z 92), were used to observe the motion of ions in a commercial quadrupole ion trap. Initially, ghost resonance peaks were observed for excitation of the precursor ion at q_z values of 0.4 and 0.5 on the q_z axis of the stability diagram. Further experiments involving the generation of two-dimensional contour plots confirmed that these ghost peaks, which were in agreement with mathematical equations describing the motion of ions in a quadrupole field, arose due to waveboard artifacts. Two-dimensional contour surface plots showed non-linear secular frequency canyons from a q_z value of 0.5 to higher values corresponding with higher drive radio frequency (rf) voltages on the stability diagram. This observation confirmed that ions are subjected to non-linear effects in this mass scan range. The octapole and hexapole field lines were observed at q_z values of 0.65 and 0.78, respectively.