Mass Defect Filter for Removing Noise and Detector Oscillation Artifacts in Centroided Time-of-Flight Mass Spectra

Spurious peaks in
centroided mass spectra resulting from detector
oscillation or “ringing” can be identified by their
unusual mass defects. Mass defect plots (fractional m/z vs measured m/z) for the single-charge mass spectrum of a pure compound show data
points falling along lines with well-defined slopes. Detector oscillation
and electronic noise peaks were removed from database spectra of pure
compounds and mixtures by eliminating points outside two standard
deviations of the slope of the major peaks. No loss of chemical information
was observed, even for compounds with isobaric fragment peaks.