field desorption

2. BY
ABDUL QAYOOM MUGHERI
Mphil scholar
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3. Introduction
Experimental techniques
Ionization sources
Mechanism
Comparison FD and FI
Advantages
Applications
Conclusion
Acknowledgment
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4. Field desorption has been
considered as offspring of
field ionization and thus the
principles governing the ion
formation have traditionally
been treated in more or less
similar way.
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5. Desorption
Removal of a substance from
a surface on which it is
adsorbed

6. FD was developed by H.D.Beckey in
1969.
A term used to describe the
formation of ions in the gas phase
from a material deposited on a solid
surface (known as an 'emitter') in
the presence of a high electrical
field.
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7.  The development of the experimental
techniques of field desorption- MS Various
types of emitter different sample loading
techniques are also.
 Automatic FD emitter heating devices and
laser assisted.
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8. Field Desorption analyses feature
the following:
•Suitable for high molecular mass and/or thermally
labile substances such as polymers, peptides,
carbohydrates and organic or inorganic salts.
•A solution of the sample is applied to the emitter
before it is introduced into the ion source.
•The emitter is mounted on the tip of the axial
sample introduction probe.

9. Field Ionization – gas is passed over
ionization source
Field Desorption – dipped in solution
containing sample and placed back in
spectrometer
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10. Field ionization (FI) is a method that uses
very strong electric fields to produce ions
from gas-phase molecules.
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11. FI FD
Sample is heated in
a vacuum so as to
volatize it onto an
ionization surface.
FI is suited for use
with volatile,
thermally stable
compounds.
The sample is placed
directly on to the
surface before
ionization.
FD is used for
nonvolatile compounds
or thermally labile
substances.
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13.  FD is perfectly suited for the analysis of
synthetic polymers or man made polymer.
 examples . Poly siloxane,poly
phospazene,Backelite,Nylon etc.
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It was the major advance
development of field
desorption Mass
spectrometry. It was
introduced by
H. B. Linden
in 2000.

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Liquid injection FD
ionization a new tool
for soft ionization of
sample include non
polar H/Cs.

16. FD M-S is used to investigate
almost any major class of organic
and in-organic.
 the main targets are substances
which cann,t be evaporized
undecomposed prior to
ionization.
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FD MASS SPECTROMETRY
APPLIED TO COAL RESEARCH
The fossil fuel research program has greatly benefited
from the availability of on-site.
The applications include (a)
differentiating coal types (b) analyzing coal tars, (c)
determining the fate of a nitrogen-containing donor
solvent in coal (d) identifying species responsible for
catalyst deactivation.

18. Many earlier applications of FD to analysis the
polar and nonvolatile analytes such as
polymers and biological molecules.
FD can produce simple mass spectra with
molecular information from hydrocarbons
and other particular analytes.
 It is important in pharmaceutical,biochemistry
and medicine.
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19. 1. Low Typically less than 1000 Da.in FI
2. . Low-moderate, depends on the sample.
Typically less than about 2,000 to 3,000
Da.in FD
3. Some examples have been recorded from
ions with masses beyond 10,000 Da
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20. FD was virtually unique in being
able to ionize non volatile polar
organic and inorganic
molecules.
Simple mass spectra,typically
molecular like ion species per
compound.
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21. 1. Field desorption mass spectrometry by laszlo
prokri
2. Beckey H.D. Field ionization mass
spectrometry. Research/Development, 1969,
20(11), 26
3. HB Linden, Liquid injection field desorption
ionization: a new tool for soft ionization of
samples including air sensitive catalysts and
non-polar hydrocarbons, Eur. J. Mass
Spectrum. 2004, 10, 459-468
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thankful to Almighty Allah Who provided me
this fabulous opportunity.
I am grateful to Prof:Dr. Shahabuddin Memon
for his precious unassuming efforts and I am
thankful to my classmates for wonder
Co-operation.

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