Modeling Known Sources of Mass Calibration Deviations in High Resolution ToF MS

Abstract

Modern time-of-flight mass spectrometer instruments exhibit excellent mass accuracy in the parts per billion range. At this level, mass calibration methods should consider potential distortions in the basic calibration. Factors which can cause distortions are to be under control. We have analytically modeled and numerically verified the influence of the main causes of mass calibration distortions, including the uncompensated dependence of flight time on the starting position, spatial gradient of the accelerating field, and overshooting at the rising edge of the accelerating pulse. Additionally, the relativity correction has been taken into account.

Crowd control of ions in the Astral analyzer

“…Instead of relatively benign self‐bunching, in‐peak resonant space charge causes loss of resolution at ~10 2 charges. This was thought to occur due to loss of the temporal focus as ions of divergent energy are pushed to higher/lower amplitude, respectively, causing times of flight to shift as a function of energy, degrading and effectively drawing the focal plane away from the detector surface 14 . Coalescence effects in MR‐ToF analyzers are also very much in evidence, for example, merging the MRFA peptide doublet at m/z 526.26 and 526.27 with less than 10 3 charges in the doublet 15 …”