Mass Spectrometry – Focus on Proteomics
Introductory Example:  mass spectrum of water
•  Electron Impact (EI)   -   Hard (fragments) / 1000 Da
H2O  + fast electron  à  [H2O]+   +  2 electrons
+ fragments ([OH]+, O+, H+)
[H2O]+     18
[OH]+       17
O+       16
H+              1
Mass-to-charge ratio
Text Box: Relative Abundance
Relative Abundance
Fragmentation pattern
(“fingerprint”)
Molecular Ion
18