Stored waveform simultaneous mass-selective ejection/excitation for Fourier transform ion cyclotron resonance mass spectrometry

Abstract

Compared with prior single-frequency or frequency-sweep excitation, the recently demonstrated stored waveform inverse Fourier transform (SWIFT) technique can produce any desired discrete frequency-domain excitation power spectrum with more uniform magnitude and higher mass selectivity. In particular, SWIFT can produce a power spectrum with multiple segments of different magnitude to achieve simultaneous high-power ejection of ions of selected m/z range(s) and low-power excitation of ions of other m/z range(s). The SWIFT technique can effectively compress a multiple excitation event sequence by combining the ejection and excitation periods. The combined ejection/excitation period can thus be made either longer (for higher mass selectivity) or shorter (to reduce the extent of ion/molecule reactions during the excitation period) than temporally distinct ejection and excitation. Simultaneous ejection/excitation at a mass resolution greater than 20 000 is demonstrated experimentally for 13C 12C 6H 7 + and 12C 7H 8 + at nominal m/z = 92.