In mass spectrometry, 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 technique where laser energy is absorbed by a matrix to create ions from large molecules 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.
| Compound | Abbreviation | Structure | Wavelength (nm) | Applications |
|---|---|---|---|---|
| 9-aminoacridine[1] | 9AA |  | 337 | lipids, metabolites |
| α-cyano-4-hydroxycinnamic acid[2] | CHCA |  | 337, 355 | peptides, lipids, nucleotides |
| ferulic acid[3][4] | FA |  | 337, 355, 266 | proteins |
| 2,5-dihydroxy benzoic acid|[5] | DHB |  | 337, 355 | peptides, nucleotides, oligonucleotides, oligosaccharides |
| 3-hydroxy picolinic acid[6] | HPA |  | 337, 355 | oligonucleotides |
| picolinic acid[7] | PA |  | 266 | oligonucleotides |
| sinapinic acid[3][4] | SA |  | 337, 355, 266 | peptides, proteins, lipids |
Matrix-assisted ionization
Matrix-assisted ionization is an ionization method in mass spectrometry that creates ions via the creation of particles at atmospheric pressure and transfer to the vacuum of the mass analyzer.[8]
| Compound | Abbreviation | Structure |
|---|---|---|
| 2,5-dihydroxybenzoic acid | DHB | |
| 2-aminobenzyl alcohol | ||
| anthranilic acid |  | |
| 2-hydroxyacetophenone |  |
Fast atom bombardment
FAB uses a high energy beam of atoms directed at a surface to create ions.[10] FAB matrix compounds are typically liquids.
| Compound | Abbreviation | Structure |
|---|---|---|
| glycerol |  | |
| thioglycerol |  | |
| 3-nitrobenzyl alcohol | NBA |  |
| 18-crown-6 ether |  | |
| 2-nitrophenyloctyl ether | NPOE |  |
| diethanolamine |  | |
| triethanolamine |  |