MALDI
Definition
Matrix-Assisted Laser Desorption / Ionisation. A soft method that uses a UV-absorbing matrix to ionise large biomolecules. Almost always paired with a TOF analyser.
Related terms
- Base Peak
- The most intense peak in a mass spectrum, normalised to 100 percent relative abundance. All other peaks in the spectrum are reported...
- EI (Electron Ionisation)
- Hard ionisation at 70 eV. Produces extensive fragmentation, ideal for library search. Standard ion source in GC-MS.
- ESI (Electrospray Ionisation)
- Soft ionisation at atmospheric pressure for polar and thermally fragile analytes in solution. Standard source in LC-MS for drugs and biomolecules.
- Fragmentation
- Breakdown of the molecular ion into smaller charged and neutral pieces. The fragmentation pattern is the chemical fingerprint that identifies the compound.
- Molecular Ion (M+)
- The intact ionised molecule with no fragmentation, formed by removing a single electron from the parent. Its m/z gives the molecular weight...
- M/z (Mass-to-Charge Ratio)
- The x-axis of every mass spectrum. Ions are separated by their mass divided by the number of charges they carry. For singly-charged...
- Nitrogen Rule
- An organic molecule with an odd-numbered molecular weight contains an odd number of nitrogen atoms. A staple trick for narrowing down a...
- TOF (Time-of-Flight)
- Mass analyser that separates ions by their flight time down a field-free drift tube. Theoretically unlimited mass range, very high speed.
Explained in
- Mass Spectroscopy: Principles, Instrumentation and Forensic ApplicationsMatrix-Assisted Laser Desorption / Ionisation. A soft method that uses a UV-absorbing matrix to ionise large biomolecules. Almost always paired with a TOF anal...