Evaluation of different combinations of gated trapping, RF-only mode and trap compensation for in-field MALDI Fourier transform mass spectrometry.

MALDI, while providing advantages such as the ability to do in-depth and repeated exploration of the sample, challenges the existing performance capabilities of Fourier transform mass spectrometry (FTMS). The challenge arises because MALDI-produced ions have high mass-to-charge ratios and uncertain kinetic-energy distributions. We demonstrate that a combination of a gated trapping event, a RF-only mode pressure focusing event, and an electrically compensated trap provides a compelling advantage in meeting these challenges. Removal of any of the above combination elements significantly degrades the detection performance of substance P from 850 K resolving power at 34.9 kHz and of melittin from 278 K resolving power at 16.5 kHz when using a 3-Tesla magnet-based spectrometer.