Open AccessPhase Correction of Fourier Transform Ion Cyclotron Resonance Mass Spectra Using MatLab
Author(s) -
Yulin Qi,
Christopher J. Thompson,
Steve L. Van Orden,
Peter B. O’Connor
Publication year - 2011
Publication title -
journal of the american society for mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.961
H-Index - 127
eISSN - 1879-1123
pISSN - 1044-0305
DOI - 10.1007/s13361-010-0006-7
Subject(s) - chemistry , fourier transform , computational physics , fourier transform ion cyclotron resonance , phase (matter) , quadratic equation , quadratic function , magnitude (astronomy) , spectral density , spectral line , mode (computer interface) , analytical chemistry (journal) , mass spectrometry , physics , mathematical analysis , mathematics , statistics , geometry , organic chemistry , chromatography , astronomy , computer science , operating system
FT-ICR mass spectrometry has been limited to magnitude mode for almost 40 years due to the data processing methods used. However, it is well known that phase correction of the data can theoretically produce an absorption-mode spectrum with a mass-resolving power that is as much as twice as high as conventional magnitude mode, and that it also improves the quality of the peak shape. Temporally dispersed frequency sweep excitation followed by a time delay before detection results in a steep quadratic variation in the signal phase with frequency. Viewing this, it is possible to find the correct phase function by performing a quadratic least squares fit, modified by iterating through phase cycles until the correct quadratic function is found. Here, we present a robust manual method to rotate these signals mathematically and generate a "phased" absorption-mode spectrum. The method can, in principle, be automated. Baseline correction is also included to eliminate the accompanying baseline drift. The resulting experimental FT-ICR absorption-mode spectra exhibit a resolving power that is at least 50% higher than that of the magnitude mode.