Improving the Performances of a "Brick Mass Spectrometer" by Quadrupole Enhanced Dipolar Resonance Ejection from the Linear Ion Trap.

Previously, a miniature mass spectrometer driven by a sinusoidal frequency scanning technique, named as Brick mass spectrometer, was developed in our lab ( Jiang et al. Anal. Chem. 2017 , 89 , 5578 ). The frequency scanning technique enabled miniaturized electronics and broader mass range, but it was also limited in reduced mass resolution and sensitivity due to a relatively low operating radio frequency (rf) voltage in comparison with the conventional voltage scanning technique. To improve performances of the Brick mass spectrometer, a quadrupole enhanced dipolar resonance ejection (QE-dipolar resonance ejection) method was proposed in this work. After optimization, mass resolution and sensitivity of the Brick mass spectrometer could be improved by no less than 2 times, and space charge effects within the ion trap could also be reduced. Furthermore, this QE-dipolar resonance ejection method is effective at elevated pressures, which would potentially allow us to further miniaturize the Brick mass spectrometer by operating it at higher pressures. This method is also applicable to any ion trap operated in either frequency scanning mode or voltage scanning mode and operated in either miniaturized instruments or benchtop instruments.