Infrared matrix-assisted laser desorption/ionization quadrupole ion trap mass spectrometry

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Eur. J. Mass Spectrom. 8, 263 - 271 (2002)
DOI: 10.1255/ejms.498

Infrared matrix-assisted laser desorption/ionization quadrupole ion trap mass spectrometry

Timothy Lippa, Nelli I. Taranenko and Vladimir M. Doroshenko^*
MassTech Inc., Subsidiary of SESI, 4032-A Blackburn Lane, Burtonsville, MD 20866, USA. E-mail:
Coorg R. Prasad
Science and Engineering Services Inc., 4032 Blackburn Lane, Burtonsville, MD 20866, USA

ABSTRACT:

Performance characteristics of an infrared (IR) matrix-assisted laser desorption/ionization (MALDI) quadrupole ion trap (QIT) mass spectrometer are presented. Both an IR laser and an ultraviolet ( UV) laser have been coupled to the MALDI ion source, allowing for a comparative study of the spectra obtained for the same analyte molecules taken at these two wavelengths. The mass range of the QIT instrument was extended by operating it at a frequency as low as 200 kHz. The results presented for small and medium-size peptides demonstrated a lesser degree of analyte ion fragmentation in the case of the IR-MALDI source compared with that obtained using the UV-MALDI source. Due to the fragmentation phenomenon, the mass resolution for cytochrome C ions (MW 12384 Da) was an order of a magnitude higher in the case of IR-MALDI compared with the use of UV-MALDI. This phenomenon has been shown to effect the calibration of the trap instrument for higher masses.

Keywords: matrix-assisted laser desorption/ionization, infrared laser, ultraviolet laser, quadrupole ion trap mass spectrometer, time-of-flight mass spectrometry, peptide ion fragmentation, HIV envelop protein fragment 421-338, dynorphin A, bovine insulin, horse heart cytochrome C, gramicidin S

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