Ultrahigh-resolution fourier transform mass spectrometry of biomolecules above m/z 5 000

✍ Scribed by Yunzhi Li; Richard L. Hunter; Robert T. McIver Jr.

• Book ID: 104307516
• Publisher: Elsevier Science
• Year: 1996
• Tongue: English
• Weight: 939 KB
• Volume: 157-158
• Category: Article
• ISSN: 0168-1176
• DOI: 10.1016/s0168-1176(96)04398-4

✦ Synopsis

Ions with a mass-to-charge ratio (m/z) greater than 5000 have been made by matrix-assisted laser desorption/ionization (MALDI) and detected at high mass resolving power by Fourier transform mass spectrometry (FTMS). The FI'MS instrument used for the investigations has a MALDI source mounted outside of the magnetic field in a separate, differentially-pumped chamber. Ions were extracted from the source and transported efficiently to the FI'MS analyzer cell by a r.f.-only quadrupole ion guide. To optimize the mass resolution for high mass ions, the operating parameters of the instrument were varied systematically. It was found that the parameters for formation of ions in the MALDI source, such as laser irradiance and amount of sample ablated, do not affect the mass resolution significantly. The biggest effects resulted from changing the ion detection parameters in the FI'MS analyzer cell, in particular the trapping voltage, excitation r.f. level, background pressure, and number of ions stored. With optimal tuning, the external ion source FTMS method gave a mass resolving power of M/AA4112 = 830 000 for human insulin at m/z 5 807 and 81000 for cytochrome C at m/z 12 360.