Mass Spectrometry – Source
Source:  produces charged particles (ions)
•    Electron Impact (EI)   -   Hard (fragments) / 1000 Da
•    Chemical Ionization (CI) – (methane / isobutane / ammonia)
•    Fast Atom Bombardment (FAB) – 6keV xenon atoms
•    Electrospray Ionization (ESI)  -  Soft / 200kDa
•    Matrix-Assisted Laser Desorption Ionization  - Soft / 500kDa