1. NUCLEAR MAGNETIC RESONANCE
SPECTROSCOPY
Dept. of Pharmaceutical analysis
SREE DATTHA INSTITUTE OF PHARMACY,
Sheriguda, Ibrahimpatnam, Hyderabad, 501510.
Presented by:
SARIA NOUSHEEN 16U21R0005
(B. Pharmacy 4th year)
Under the guidance of
Asst. Professor Mrs. Sadhana
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3. INTRODUCTION:-
Nuclear Magnetic Resonance(NMR) is a spectroscopy
technique which is based on the absorption of
electromagnetic radiation in the Radio Frequency
Region 4 TO 900 MHz by nuclei of the atoms.
Proton Nuclear Magnetic Resonance Spectroscopy is one
of the most powerful tool for elucidating the number of
hydrogen or proton in the compound.
it is used to study a wide variety of nuclei
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4. PRINCIPLE OF NMR
The theory behind NMR comes from
any nucleus or proton with odd mass
number ,the nucleus spins on its own
axis in random directions and a
magnetic momentum is created with
an external magnetic force.
Due to application of external
magnetic force,the nucleus align
themselves either with or against the
field of external magnet.
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5. if External Magnetic field is applied , an
energy transfer is possible between ground
state to excited state.
when the spin returns to the ground
state level, the absorbed radio frequency
is emitted at same frequency level.
The emitted radiofrequency signal that
give the NMR spectra of the concerned
compound.
the emitted radiofrequency is directly
proportional to the strength of applied
field.
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7. NMR SPECTRUM
The NMR spectrum is a plot of Intensity of NMR signals
vs Magnetic field(frequency) in reference to
TetraMethlysilane (TMS)
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8. NMR INSTRUMENTATION
In any NMR instrument the main components are:
1.Sample holder
2.Permanent Magnet
3.magnetic coils
4.Sweep Generator
5.Radio frequency Transmitter
6.Radio frequency Receiver
7.Readout devices.
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10. Block diagram of NMR
spectrophotometer
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11. 1.Sample Holder:
Glass or pyrex tubes are
generally used.
These are sturdy ,practical
and cheap .
Chemically inert and are
transparent to allow the RF
radiations to pass through.
They are usually about 25cm
long and 5mm in diameter .
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12. 2.Permanent Magnet:
It provides homogeneous magnetic field at 60 to
100MHz
a combination of radiofrequency and magnetic strength
is used where the radiofrequency is kept constant.
3.Magnetic coils:
These coils induce magnetic field when current
flows through them.
4.Sweep Generator:
To vary the strength of applied magnetic field i.e.
to sweep magnetic field.A field strength of 14,092 gauss,
21,140 gauss or 23,490 gauss is used,depending on the radio
frequency region employed.
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13. 5.Radio frequency transmitter:
It is used to apply radio frequency radiations
(ex:)60MHz,100MHz,220MHz,300MHz,400MHz
depending upon the instrument.
6.Radio frequency receiver:
Used to measure the intensity of unabsorbed
radio frequency energy.
7.Readout Devices:
A computer that analyses and record the data
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14. Solvents used in NMR
The analysis of organic compounds for nature, type,
number and environment of protons (Hydrogens),the
solvents used in NMR should not contain Hydrogen atoms .
Hence the solvents used in NMR are as follows:
CCl4 - carbon tetrachloride
CS2 - carbon disulphide
CDCl3 - Deuterated chloroform
D2O - Deuterated water
CD3OD - Deuterated acetic acid
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15. Properties of solvents
THE FOLLOWING PROPERTIES SHOULD THE
SOLVENTS HAVE
1.Chemical inertness
2.Magnetic isotropy(magnetically neutral)
3.volatility(to facilitate sample recovery)
4.Absence of Hydrogen atoms
5.Easily available and inexpensive.
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16. APPLICATIONS OF NMR
1.Structure elucidation of organic compounds
2.Investigation of dynamic properties of the molecules
like conformational isomerism, molecular asymetry,
hydrogen bonding etc.. can be done
3.Determination of optical purity
4.Quantitative analysis which include
a. Assay of components
b. Surfactant chain length determination
c. Hydrogen analysis
d. Iodine value
e. Moisture analysis
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