Research Equipment
Matrix-Assisted Laser Desorption Ionization & Time Of Flight Mass Spectrometer (MALDI-TOFMS)
The following is a description of the Matrix-Assisted Laser Desorption Ionization & Time Of Flight Mass Spectrometer (MALDI-TOFMS) housed on the 1st floor of our Electron Microscope Building.
Firstly, please tell me about MALDI-TOFMS.
Mass spectrometry measures the mass of molecules by measuring the mass-to-charge ratio (m/z). MALDI (Matrix-Assisted Laser Desorption/Ionization) is a soft ionization technique and TOF-MS (Time Of Flight Mass Spectrometry) is method of mass analysis.
MALDI is an ionization technique in which a sample is irradiated with a laser beam, isn't it?
That's correct. The sample is cocrystallized with a matrix compound in about a 1/1000 molar ratio. Ionization occurs when the dried matrix is irradiated with a focused laser beam in the mass spectrometer ion source region. A matrix is used to protect the biomolecule such as protein from being destroyed by direct laser beam and to facilitate vaporization and ionization.
What kind of method is TOF-MS?
In TOF analyzers the mass to charge ratio of an ion is determined by measuring its flight time. After acceleration of the ions in the ion source to a fixed kinetic energy, they pass a field free drift tube with a velocity proportional to mass-to-charge ratio. Due to their mass-dependant velocities, ions are separated during their flight. Lighter ions drift more quickly to the detector. Heavier ions drift more slowly.
Are ions speed measured by apparatus such as radar gun used in baseball?
Radar gun relies on the Doppler effect applied to a radar beam to directly measure the speed of objects. However, case of speed measurement
via TOF MS be calculated using the formula:
(Speed)= (Distance)/ (Time)
Speed is measured from drift distance per unit of drift time.
What is the advantage of using MALDI-TOFMS?
The advantage of MALDI over other methods is that it ionizes biological materials (such as proteins, peptides, glycans, and oligonucleotides)
without destroying them. MALDI-TOF MS can analyze theoretically unlimited mass range, greater than 30,000 daltons (Da). Mass range is limited by
ionization ability, not analyzer physics. As other aspect of advantage, MALDI instrument is used for monitoring rapid phenomena such as chemical
reaction.
There are various types of mass analysis instrument in JAIST. It is very important to select appropriate ionization method and analysis instrument.
