maldi & ldi , main difference, how they help in ionization peocess & how they actually ionize the sample in mass spectrometry. their applications, significance & limitations.

1. LASER DESORPTION
IONIZATION
(MALDI)
BY:
WISHAL BUTT

2. CONTENTS:-
•Introduction
•History
•Principle
•Working
•Applications
•Advantages
•Disadvantages

3. Laser desorption
ionization:-

4. • LASER:
light amplification by stimulated
emission of radiation.
•DESORPTION:
release of substance through or
from a surface.
•IONIZATION:-
• attaining of charge by gain or
loose of electrons.

5. • Sample is irradiated directly
with pulsed laser beam.
• Molecules absorb energy, gain
or lose of electrons & ions are
formed.
• Hard ionization

6. HISTORY:-
•In 1985 Franz
Hillenkamp and
Michael Karas
• in 1987 Tanaka used &
got Nobel prize.

7. MALDI:-
•MATRIX ASSISTED
LASER
DESORPTION
IONIZATION

8. INTRODUCTION:-
• MATRIX ASSISTED LASER
DESORPTION IONIZATION.
• Soft ionization technique
• Analysis of biomolecules & large
organic molecules.
• Pulsed laser beam trigger ionization.
• Determine molecular weight of
peptide, antibodies, proteins ,
Lipids, saccharides.

9. PRINCIPLE:-
•Analyte is uniformly mixed
with large quantity of
matrix that absorbs the
pulsed UV radiations &
vapourized into the
vacuum well being ionized
at the same time

11. SAMPLE
PLATE:-

12. MATRIX:- (key to success)
Compound Solvents Wavelength Applications
2,5-Dihydrobenzoic
acid
acetonitrile,
water, methanol,
acetone, chloroform
337, 266, 355 Peptide, nucleotide,
oligonucleotide,
oligosaccharides
Picolinic acid Ethanol 266 oligonucleotide
4-hydroxy 3-methoxy
cinnamic acid
Acetonitrile, water,
propanol
337, 266, 355 proteins

14. LASER:-
•337nm nitrogen laser
(UV region).
•335nm frequency
tripled Nd:YAG lasers.
•10.6um carbon
dioxide laser.

16. WORKING:-
• Consist up of three
steps:
1. Sample
preparation
2. Matrix excitation
3. Analyte
ionization

17. Sample preparation:-
•Same solvent
•Increased conc.
of matrix than
analyte

18. Matrix excitation:-
•Pulsed laser beam
focused on sample .
•Solvent evaporates
•Matrix absorbs photon
energy (excitation)
•Conversion into gas
phase.

19. Analyte ionization:-
Photon transfer to
analyte.
Loss / gain of electron
Cation formation
Ions use for MS
analysis

21. Applications:-
•Large molecule
identification.
•Identification of
microorganisms.
•Disease diagnosis

22. ADVANTAGES
 parent ions
Accurate & sensitive
Cost effective
Rapid & reliable
DISADVANTAGES :-
No fragment library
Less sensitive without prior culture
Detection limit

23. REFERENCES:-
• Identification of Adult Fasciola spp. Using Matrix-Assisted
Laser/Desorption Ionization Time-of-Flight (MALDI-TOF)
Mass Spectrometry.
• Article MALDI TOF Mass Spectrometry Imaging of Blood Smear:
Method Development and Evaluation.
• Analytical chemistry by GARY D Christian.
•http://www.laserscience.com/maldi_tof.htm
• https://en.wikipedia.org/wiki/Matrix-assisted_laser_desorption/ionization
• y/maldi.shtwww.niu.edu/clas/chembio/research/analytical-lab/mass-spectroscopml