Introduction,Instrumentation, chemical shift , Applications of NMR

1. PRESENTED BY
UJJWAL MANDAL
M.PHARM, 1ST SEM, 1ST YEAR
INTRODUCTION ,
INSTRUMENTATION &
APPLICATIONS OF NMR

2. CONTENTS
 INTRODUCTION
 PRINCIPLE
 SHIELDING AND DESHIELDING
 CHEMICAL SHIFT
 INSTRUMENTATION
 APPLICATIONS OF NMR
 CONCLUSION
 REFERENCES
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3. INTRODUCTION OF NMR
 Nuclear magnetic resonance spectroscopy or NMR
is a powerful analytical technique used to characterize
organic molecules by identifying carbon-hydrogen
frameworks within molecules.
 Two common types of NMR spectroscopy are used…..
: 1H NMR is used to determine the type and number of
H atom in a molecule.
: 13C NMR is used to determine the type and number of
C atom in a molecule.
 The source of energy in NMR is radio waves, which
have long wavelength.
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4. PRINCIPLE
 Nuclei with odd mass number(1H, 13C, 19F, 35Cl etc.)
only give NMR spectra. Spin quantum number (I) for
such nuclei will be 1/2,3/2,5/2 etc.
For example, 1H
I = ½ &
Total possible orientation state(2I+1)=2
1.Ground state (-1/2)
2. Excited state(+1/2)
 Other nuclei with even mass number & even atomic
number do not give NMR spectra. Like 12C, 16O8,
Nuclei whose spin number, I=0 have no NMR spectra.
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5.  The theory behind NMR comes from
the spin of nucleus and it generates a
magnetic field. Without an external
applied magnetic field, nuclear spins
are random in direction.
But when an external magnetic applied
then the nuclei aligns themselves either
with or against the field of the external
Magnetic direction.
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THEORY

6. ARRANGEMENT SYSTEM
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7. SHIELDING AND DESHIELDING EFFECT
 When a proton is present inside
such magnetic field, then more
applied magnetic field is required
for excitating. This protons are
known as shielded protons.
 When a proton is present outside
such circulating magnetic field,then
less applied magnetic field is
required for excitating.This
protons are known as deshielded
protons.
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8. CHEMICAL SHIFT
 Chemical shift is the difference between the absorption
position of the sample proton and the absorption of the
reference standard (e.g. TMS).
 Variations of the positions of NMR spectra due to the
electronic shielding or deshielding effect.This
phenomenon known as spin-spin coupling (splitting).
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9. INSTRUMENTATION
1. RF transmitter- It is use for to apply a
radiofrequency radiation. E.g.
60Mhz,100Mhz,220Mhz,300Mhz depending on the
capacity of instrument.
2. RF receiver/detector- It is use to measure the
intensity of unabsorbed radio frequency energy.
3. Sweep Generator – To vary the strength of the
applied magnetic field. A field strength of 14,092
gauss,21,140 gauss etc are used.
4. Sample cell – A sample test tube, which is about
25cm long and 5mm outer diameter is kept inside the
sample cavity and is spun at 30rps.
5. Recorder – It is used to record the NMR signal
obtained from detector. 9

10. SCHEMATIC DIAGRAM
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11. APPLICATIONS OF NMR
 To characterize of molecular structure and nature.
 Determines purity and composition of a sample.
 Types and number of proton, carbon.
 Environment of proton, whether the proton is shielded
or deshielded.
 Moisture analysis :- The % of hydrogen in the
compound can be determined.
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12. CONCLUSION
 Nuclear magnetic resonance spectroscopy is one of
the most powerful tools that use to determine the
structure of compounds. Generally, NMR spectroscopy
gives the information about organic and inorganic
compound.
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13. REFERENCES
1. Dr. S. Ravi Sankar,Text book of Pharmaceutical
Analysis,4th edition,2010,Page-(6.1-6.9)
2. Y.R. Sharma,Elementary Organic Spectroscopy,5th
edition,2015,Page-(191-241)
3. Gurdeep R. Chatwal, Sham K. Anand, Instrumental
Methods of Chemical Analysis,Himalaya Publishing
House,2017,(Page-2.185-2.235)
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