Brief introduction about Mass Spectroscopy & its Instrumentation.

1. Bhavana vedantam,
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2. Contents
Introduction
Basic principle
Advantages & Disadvantages
Instrumentation
Applications
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3. •
Mass spectroscopy deals with the study of the charged
molecules & fragment ions produced from a sample
exposed to ionizing conditions, & also of the relative
intensity spectrum which results from the correlation of the
ions with their mass to charge ratio.
• MS concept is first introduced by scientists
Sir.J.J. Thomson and Wiens.
Powerpoint Templates
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4. Principle to 10
When gaseous sample under 10
-7
-5 mm
Hg
pressure bombarded with electron beam(70ev), loss of
electron from π orbital takes place resulting in the
formation of ions and ion fragments.
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5. Molecular
ions
Fragment
ions
Isotopic
ions
Types of ions
Rearrangement
ions
Multiple
charged
ions
Negative ions
Meta
stable
ions
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7. Molecular weight &
formula
determination
Qualitative &
Quantitative
analysis
Sample destruction
Sample should be in
gaseous form
Less amount of
sample
Complex & high cost
Less than 1min. for
analysis
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Should maintain
vacuum throughout
the process
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10. solid
Directly into the
chamber with low
vapour pressure
by means of
probe.
e.g. steroids,
carbohydrates
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Liquid
Vaporized with
the help of heat
inlet system.
e.g. sugars ,
amino acids
Gas
Directly inleted &
vaporized
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11. Ionization techniques
Electron
impact
ionization
Chemical
ionization
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Field
ionization
Laser
desorption
technique
Fast acting
bombardme
nt
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12. Electron beam(70ev) produced from electrically heated tungsten
or rhenium filament is applied perpendicular to the sample and
results in fragmentation.
*sample destruction.
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13. Reactive gases bombards with
electron beam
Reactive species are formed which
colloid with sample molecules
+vely charged ions are produced
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14. Fast atoms
of Xe/Ar
collides
with neutral
gas atoms
Transfer of
energy to
gas atoms
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High
energy gas
atoms
directed
towards
sample
Energy
transfer to
sample
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15. Eg: MALDI(Matrix Assisted Laser
Desorption Ionization)
• TOF (Time Of Flight) analyzer
Advantages :
No direct contact of sample and electron
Easy to operate
laser
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4-hydroxy
cinnamic acid
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16. Contd…….
Matrix
+
+
+ +
Laser
Analyte
+
+ +
+ + -+
+
+
+
+
+
Laser is bombarded with
Matrix containing the sample
Energy transfer to sample
Expansion of matrix
+
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17. +ve ions at the end of
chamber
Bombarded with
accelerating
potential(2-8kV)
Analyzers are
used to deflect
ions based upon
m/e ratio.
Deflection in magnetic
field according to
velocity & m/e
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20. Magnetic field
Magnetic field &
electric field
Ions of same mass
number are
separated
Ions of same mass
no.& same velocity
are separated
Less
sensitivity(10-1)
Highly
sensitive(10-12)
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22. Faraday
Cup
detector
Least
sensitive.
Cup will
capture the
ion.
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Photomult
iplier
detector
sensitive.
1000 times
greater than
faraday cup.
Photogra
phic
detectors
Most
sensitive.
Used for
high
resolution.
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23. APPLICATIONS
Molecular weight,formula & elemental
composition determination
Identification of an unknown compound
Distinction between cis & trans- isomers
Identification of fragmentation pattern
Impurity detection
As LC-MS in analysis of proteins
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24. • Mass spectrometry is used for the study of
charged molecules and fragment ions. Thus
it is useful for the identification of an
unknown compound.
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25. • Elementary organic spectroscopy by
Y.R.Sharma fourth edition 2007,by Rajendhra
Ravindra printers page(280-291).
• Spectroscopy of organic compounds by P.S.Kalsi
sixth edition, by New age international Pvt. Ltd.
Page(415-439).
• Gurdeep R.Chatwal Sham K. Anand Instrumental
Methods Of Analysis, Fifth addition, Himalaya
publishing house Pvt . Ltd.
• Pharmaceutical analysis (INSTRUMENTAL
METHODS) by Dr . A.V.Kasture, ninth edition.

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