Ilse Katz Institute for Nanoscale Science & Technology

MALDI-TOF MS overview

Mass Spectrometer Autoflex speed™ MALDI TOF/TOF

MALDI

In mass spectrometry, matrix-assisted laser desorption/ionization (MALDI) is an ionization technique that uses a laser energy absorbing matrix to create ions from molecules with minimal fragmentation. It has been applied to the analysis of biomolecules (biopolymers such as oligonucleotides, proteins, peptides and sugars) and organic molecules (such as polymers, dendrimers other macromolecules, and etc.), which tend to be fragile and fragment when ionized by more conventional ionization methods. It is similar in character to electrospray ionization (ESI) in that both techniques are relatively soft (low fragmentation) ways of obtaining ions of large molecules in the gas phase, though MALDI typically produces far fewer multiply charged ions.

MALDI methodology is a three-step process. First, the sample is mixed with a suitable matrix material and applied to a metal plate. Second, a pulsed laser irradiates the sample, triggering ablation and desorption of the sample and matrix material. Finally, the analyte molecules are ionized by being protonated or deprotonated in the hot plume of ablated gases, and can then be accelerated into whichever mass spectrometer is used to analyse them.

TOF

Time-of-flight mass spectrometry (TOFMS) is a method of mass spectrometry in which an ion's mass-to-charge ratio is determined via a time measurement. Ions are accelerated by an electric field of known strength.This acceleration results in an ion having the same kinetic energy as any other ion that has the same charge. The velocity of the ion depends on the mass-to-charge ratio (heavier ions of the same charge reach lower speeds, although ions with higher charge will also increase in velocity). The time that it subsequently takes for the ion to reach a detector at a known distance is measured. This time will depend on the velocity of the ion, and therefore is a measure of its mass-to-charge ratio. From this ratio and known experimental parameters, one can identify the molecular mass of ion.

MALDI contact person.

Dr. Mark M. Karpasas

Ilse Katz Institute for

Nanoscale Science and Technology
Ben-Gurion University of the Negev
http://web.bgu.ac.il/Eng/Centers/nano

Tel(Office): +972-8-6477989 | lab:+972-8-6479014 or +972-6428670

Fax 972-8-6428638

Beer-Sheva 84105, Israel

karpasas@bgu.ac.il

Dr. Banshatz Raisa

Ilse Katz Institute for

Nanoscale Science and Technology
Ben-Gurion University of the Negev
http://web.bgu.ac.il/Eng/Centers/nano

Tel(Office): +972-8-6477989 | lab:+972-8-6479014 or +972-6428670