In
mass spectrometry
Mass spectrometry (MS) is an analytical technique that is used to measure the mass-to-charge ratio of ions. The results are presented as a ''mass spectrum'', a plot of intensity as a function of the mass-to-charge ratio. Mass spectrometry is used ...
, a matrix is a compound that promotes the formation of
ions. Matrix compounds are used in
matrix-assisted laser desorption/ionization (MALDI),
matrix-assisted ionization (MAI), and
fast atom bombardment (FAB).
Matrix-assisted laser desorption/ionization
MALDI is an
ionization
Ionization or ionisation is the process by which an atom or a molecule acquires a negative or positive Electric charge, charge by gaining or losing electrons, often in conjunction with other chemical changes. The resulting electrically charged at ...
technique where laser energy is absorbed by a matrix to create
ions from large
molecule
A molecule is a group of two or more atoms that are held together by Force, attractive forces known as chemical bonds; depending on context, the term may or may not include ions that satisfy this criterion. In quantum physics, organic chemi ...
s without fragmentation. The matrix, typically in excess, is mixed with the analyte molecule and deposited on a target. A table of matrix compounds, their structures, laser wavelengths typically used, and typical application is shown below.
Matrix-assisted ionization
Matrix-assisted ionization is an ionization method in mass spectrometry that creates ions via the creation of particles at
atmospheric pressure
Atmospheric pressure, also known as air pressure or barometric pressure (after the barometer), is the pressure within the atmosphere of Earth. The standard atmosphere (symbol: atm) is a unit of pressure defined as , which is equivalent to 1,013. ...
and transfer to the vacuum of the
mass analyzer.
Fast atom bombardment
FAB uses a high energy beam of
atoms
Atoms are the basic particles of the chemical elements. An atom consists of a nucleus of protons and generally neutrons, surrounded by an electromagnetically bound swarm of electrons. The chemical elements are distinguished from each other ...
directed at a surface to create ions.
FAB matrix compounds are typically liquids.
See also
*
Desorption/ionization on silicon
References
{{Mass spectrometry
Mass spectrometry