Maldi TOF Mass Spectrometer (MALDI TOF MS)

MALDI TOF mass spectrometers (matrix-assisted laser desorption/ionization/time-of-flight) are amongst the most popular mass spec instruments in biology. They combine two technologies, the “soft” MALDI ionization source and the TOF mass analyzer. The latter measures an ion’s mass-to-charge ratio (m/z) by measuring the time it takes to reach a detector. The former volatilizes and ionizes those molecules using a laser, a target, and an organic compound called a matrix. In MALDI, a sample (for instance, a collection of tryptic peptides) is mixed with matrix, spotted and dried (crystallized) on the surface of a metal target plate. Upon irradiation with laser light, the matrix absorbs the energy and converts it to heat, which then causes the sample to ionize and explode off the plate into the mass analyzer. MALDI TOF mass spectrometers come in two basic flavors, MALDI TOF MS and MALDI TOF/TOF MS; the latter enables tandem MS (MS/MS) studies.