4. Mass analyzer
• Quadrupole analyzer.
• Ion trap (IT) instruments,
• time-of-flight (TOF),
• Orbitrap .
• Ion cyclotron resonance (ICR) mass
analyzers.
• ESI triple quadrupole (ESI-QQQ).
• QTOF.
5. Matrix Assisted Laser Desorption
Ionization MALDI
Beate Fuchs et.al. Progress in Lipid Research 2010.49 ,450–475
6. Alexandra P. Kafkaa et.al. International Journal of Pharmaceutics 2011,417 70– 82
Matrix
7. The matrix
MALDI TOF matrices should be:
1. embed and isolate analytes (e.g., by co-crystallization).
2. be soluble in analyte-compatible solvents.
3. vacuum-stable.
4. absorb the laser wavelength.
5. initiate co-desorption of analyte upon laser irradiation
6. promote analyte ionization .
8. Matrix Example
Both choice of matrix and sample preparation have been shown to influence the nature of
molecules that can be detected using MALDI TOF and the quality of the resulting data
9. Lipids
• 50–60% of the constituents of cell membranes.
• 20–25% of the Brain dry weight .
Importance
• provide energy for the body( lysosomes ).
• Disorder of lipid distribution cause a lot of
disease.
30. Challenge
• Presence of adduct ions [M+Na]+
, [M+K]+
from solvent.
• Contamination from solvent.
• Lateral diffusion(analyte delocalization) due to solvent.
Two solvent free techniques,
dry-coating and sublimation
31. The dry-coating technique
deposits finely ground matrix onto tissue slices
by the direct filtering of solid matrix particles
through a 20 μm stainless steel sieve.
37. Conclusion
• Sublimation is easy technique.
• Reduce contamination from the solvent.
• Generates a very even and uniformly thin layer.
• Reduction in laser spot-to-spot
38. Summary
Both Techniques” Liquid ionic and sublimation are:
Easy.
Available.
Enhance MALDI-MSI resolution.
Economically, cheap.
39. Prospective view
• Combination between Liquid Ionic Matrix with
Sublimation technique may be will enhance
the MALDI-MSI spectra.
40. Acknowledge
• Assuit university, Egypt
• National sun yat sen university, ROC.
• Prof. Hui-Fen Wu.
• Prof. jiang.
• Prof. Tseng.