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Matrix-assisted laser desorption ionization with a magnetic mass spectrometer
J A Hill1, R S Annan, K Biemann
1Department of Chemistry, Massachusetts Institute of Technology, Cambridge 02139.
Rapid Communications in Mass Spectrometry : RCM
|September 1, 1991
Summary
Matrix-assisted laser desorption ionization using a magnetic mass spectrometer achieved high resolution and sensitivity for proteins like ubiquitin. This method helps explain peak broadening in time-of-flight mass spectrometry due to metastable decomposition.
Area of Science:
- Analytical Chemistry
- Mass Spectrometry
- Biochemistry
Background:
- Matrix-assisted laser desorption ionization (MALDI) is a key technique for analyzing biomolecules.
- Previous studies often used time-of-flight mass spectrometers, which can exhibit peak broadening.
- Understanding the fundamental processes in MALDI is crucial for accurate mass analysis.
Purpose of the Study:
- To investigate MALDI using a high-mass double-focusing magnetic mass spectrometer.
- To characterize the resolution and sensitivity achievable with this setup.
- To elucidate the cause of peak broadening observed in other MALDI instruments.
Main Methods:
- Utilized a high-mass double-focusing magnetic mass spectrometer for MALDI.
- Irradiated samples (substance P, ubiquitin, cytochrome c) in 2,5-dihydroxybenzoic acid with a XeF excimer laser.
- Recorded pulsed ion signals using an integrating array detector.
Main Results:
- Achieved good spectral resolution (2600 FWHM).
- Demonstrated high sensitivity, detecting down to a few picomoles of sample.
- Observed the loss of small neutral fragments, indicating metastable decomposition.
Conclusions:
- MALDI coupled with magnetic sector mass spectrometry provides high resolution and sensitivity.
- Metastable decomposition, leading to the loss of neutral fragments, is a significant factor in peak broadening.
- This finding offers insights into ion dynamics in MALDI mass spectrometry.