Zeptomole-Sensitivity Electrospray Ionization−Fourier Transform Ion Cyclotron Resonance Mass Spectrometry of Proteins

• Published in: Analytical chemistry (Washington) Vol. 72; no. 10; pp. 2271 - 2279
• Main Authors: Belov, Mikhail E, Gorshkov, Mikhail V, Udseth, Harold R, Anderson, Gordon A, Smith, Richard D
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 15-05-2000
• Subjects: Analytical, structural and metabolic biochemistry; Biological and medical sciences; Cyclotrons; Cytochrome c Group - analysis; Fundamental and applied biological sciences. Psychology; General aspects, investigation methods; Ions; Organic chemistry; Proteins; Proteins - analysis; Spectroscopy, Fourier Transform Infrared - methods; Spectrum analysis; Fourier transformation; Analysis method; Ion cyclotron resonance; Mass spectrometry; Electrospray; Protein
• ISSN: 0003-2700; 1520-6882
• DOI: 10.1021/ac991360b

Methods are being developed for ultrasensitive protein characterization based upon electrospray ionization (ESI) with Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS). The sensitivity of a FTICR mass spectrometer equipped with an ESI source depends on the overall ion transmission, which combines the probability of ionization, transmission efficiency, and ion trapping in the FTICR cell. Our developments implemented in a 3.5 tesla FTICR mass spectrometer include introduction and optimization of a newly designed electrodynamic ion funnel in the ESI interface, improving the ion beam characteristics in a quadrupole-electrostatic ion guide interface, and modification of the electrostatic ion guide. These developments provide a detection limit of approximately 30 zmol (∼18 000 molecules) for proteins with molecular weights ranging from 8 to 20 kDa.