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MALDI demonstration
Frímann, Helgi, Long, Nanna
Sample preperation
The sample of interest and matrix are dissolved in a volatile solvent
The sample/matrix/solvent mixture is then spotted on a metal plate
When the solvent has evaporated you can put your plate in to the vacuum
Anchor chips have hydrophilic area surrounded by hydrophobic ring
Matrix Assisted Laser Desorption/ Ionization
Introduced by M. Karas and F. Hillenkamp in 1985 [1]
Mainly used for large molecules Soft ionization The vibrational energy added to the analyte
molecule is about 4eV [2] The ions formed are typically: [M+H]+, [M+Na]+,
[M+K]+, [M+NH4]+ or [M-H]-
Ionization mechanism is not fully understood
TOF mass spectrometer
A TOF MS is usually (always?) used with MALDI
Reflectron TOF MSMS Microchannel plate electron multiplier (10000
electrons for each ion) MALDI-TOF “records”: ~300.000 amu,
attomoles of material
P2+
Target Reflector Reflectorplate detector
Line
ar d
etec
tor
Drift region
Two stage fieldstrength
Optical lenses
Ion source(PIE)
P1+
PCISIS1
IS1
/ IS
2G
roun
d
IS1
IS1 / IS2 Acc
eler
atio
npo
tent
ials
Ground
P1+
P1+
Parents andfragments
1SRef
1
2
3
4
4x10
Inte
ns.
[a.u
.]
2SRef
0.50
0.75
1.00
1.25
1.50
1.75
2.004x10
Inte
ns.
[a.u
.]
3SRef
0.5
0.6
0.7
0.8
0.9
4x10
Inte
ns.
[a.u
.]
4SRef
0.50
0.75
1.00
1.25
1.50
1.75
4x10
Inte
ns.
[a.u
.]
5SRef
4000
5000
6000
7000
8000
Inte
ns.
[a.u
.]
fast
2
4
6
4x10
Inte
ns.
[a.u
.]
800 1000 1200 1400 1600 1800
m/z
Electron multiplier
Measurements
• The data we have is from the protein BSA (Bovine serum albumin)
• We took linear spectra in the demostration
• Got the data from the peak at 927amu in MSMS mode
NH2
NH
NH
NH
OH
R1
O R2
O R3
O R4
O
a1 b1 c1
x3 y3 z3
a3 b3 c3a2 b2 c2
x1 y1 z1x2 y2 z2
NH2
NH
NH
NH
OH
R1
O R2
O R3
O R4
O
a1 b1 c1a1 b1 c1
x3 y3 z3x3 y3 z3
a3 b3 c3a3 b3 c3a2 b2 c2a2 b2 c2
x1 y1 z1x1 y1 z1x2 y2 z2x2 y2 z2
References
• [1] Karas, M.; Bachmann, D.; Hillenkamp, F. (1985). "Influence of the Wavelength in High-Irradiance Ultraviolet Laser Desorption Mass Spectrometry of Organic Molecules".Anal Chem 57: 2935–9
• [2] I. Bald, J. Kopyra and E. Illenberger, Angewandte Chemie-International Edition 45 (29), 4851-4855 (2006).