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t
=
D
v
=
m
2
ZeEs
⎛
⎝⎜
⎞
⎠⎟
1/2
D
D = length of drift region
m
Z
=
2
eEs t
D
⎛
⎝⎜
⎞
⎠⎟
2
= main result (m/Z units)
MALDI-TOF: Matrix assisted laser desorption-ionization - time-of-flight
Macromolecules can be ionized and desorbed (transferred to vacuum) without
degradation:
a)
The macromolecule is embedded in a solid material (the ’matrix’)
b)
The matrix is irradiated by a high energy laser pulse.
Typical matrix: 2,5-dihydroxybenzoic acid. Absorbs UV pulse.
Pulse: simplifies data analysis, all molecules are desorbed at the same time
(synchronous).
Example: Myoglobin. Note multiple peaks. No problem because m/Z are
integers relative to Z = 1.