title: Advanced stored waveform inverse Fourier transform technique for a matrix-assisted laser desorption/ionization quadrupole ion trap mass spectrometer.
abstract: The stored waveform inverse Fourier transform (SWIFT) technique is used for broadband excitation of ions in an ion-trap mass spectrometer to perform mass-selective accumulation, isolation, and fragmentation of peptide ions formed by matrix-assisted laser desorption/ionization. Unit mass resolution is achieved for isolation of ions in the range of m/z up to 1300 using a two-step isolation technique with stretched-in-time narrow band SWIFT pulses at the second stage. The effect of 'stretched-in-time' waveforms is similar to that observed previously for mass-scan-rate reduction. The asymmetry phenomenon resulting from the stretched ion-trap electrode geometry is observed during application of normal and time-reversed waveforms and is similar to the asymmetry effects observed for forward and reverse mass scans in the resonance ejection mode. Mass-selective accumulation of ions from multiple laser shots was accomplished using a method described earlier that involves increasing the trapping voltage during ion introduction for more efficient trapping of ions.
authors.affiliation: Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
authors.forename: V M
authors.initials: VM
authors.lastname: Doroshenko
authors.forename: R J
authors.initials: RJ
authors.lastname: Cotter
mesh_terms: D000803:Angiotensin I / Q000032:analysis; D005583:Fourier Analysis; D012984:Software; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000295:instrumentation*
chemical_list: D000803:Angiotensin I