maldi demonstration frímann, helgi, long, nanna. sample preperation the sample of interest and...
TRANSCRIPT
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).