POLARIMETRY & content History, Introduction, Principle, Types of polarimeter, Instrumentation, Plane Polarized light, Applications of polarimetry, Referances.

1. A
Seminar on
Polarimetry
GUIDED BY:
DEVANSHI H. RAMI
ASSISTANT PROFESSOR
M.PHARM
PREPARED BY:
ANKITKUMAR S. VASOYA
M.Sc. Pharma Analysis
SEMESTER 2
CENTRE FOR HEALTH AND APPLIED SCIENCES (CHAS)
GANPAT UNIVERSITY, GANPAT VIDHYANAGAR,
MAHESANA-GOJARIA HIGHWAY - 384012
GUJRAT,INDIA
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2. C o n t e n t 2
• History
• Introduction
• Principle
• Types of polarimeter
• Instrumentation
• Plane Polarized light
• Application

3. H i s t o r y 3
 Polarization by reflection was discovered
in 1808 by ÉTIENNE LOUIS MALUS.
 He conducted experiments to verify
CHRISTIAAN HUYGENS’S theories of
light and rewrote the theory in analytical
form his discovery of the polarization of
light by reflection.
Étienne Louis Malus
(1775–1812)

4. I n t r o d u c t i o n 4
 Polarimetry is the measurement and interpretation of
the polarization of transverse waves.
 Polarimetry is one of the important instrumental method employ in
analysis.
 Polarimetry is a sensitive, non-destructive technique for measuring the
optical activity compounds.
 This technique involves the measurement of change in the direction of
vibration of polarized light when interact with an optically active
compound.
 A substance is said to be optically active if it rotates the plane of the
polarized light.

5. P r i n c i p l e 5
Instrument measures the rotation of polarized light
as it passes through an optically active substance
and the tendency of the molecule to rotate the plane
polarized light towards clock-wise or anti-clock wise
direction whose extent of the rotation can be
measured.

6. 6
These compounds are called as optically
active compounds or substances.
Optical activity is unique character for a
molecule.

7. T y p e s o f P o l a r i m e t e r 7
There are various types of polarimeter :
1. Laurent's half-shade polarimeter
2. Biquartz polarimeter
3. Lippich polarimeter
4. X-Ray Polarimeter
5. Quartz-Wedge polarimeter
6. Manual
7. Semi-automatic
8. Fully automatic Fully automatic
Lippich polarimeter
Manual
Polarimeter

8. 8
Light Source
Unpolarised light
Polarizer
Polarizer Light
Sample tube containing
organic molecules
30° optical rotation
Movable analyser
Observe
I n s t r u m e n t a t i o n

9. P l a n e P o l a r i s e d L i g h t 9
According to wave theory of light, an ordinary ray light is
considered to be vibrating in all planes at right angle to the
direction of propagation.
If this ordinary ray of light is passed through a Nicol
prism, the emergent ray has its vibration only in one
plane. This light having wave motion in only
one plane is known as Plane Polarised Light.

10. P o l a r i z e r & A n a l y s e r 10
A polarising filter transmits only light in
a certain polarisation direction and
suppresses the light of other
polarisation directions. Light which has
passed through a polarising filter is
called polarised.
When polarised light passes through a
second filter placed parallel to the first
filter. If the second filter is rotated by
90°, it suppresses the polarised light
beam; the screen behind it remains
dark.

11. 11S p e c i f i c R o t a t i o n
= specific rotation𝛼 𝜆
𝑇
Where,
λ = wavelength of light
T = the temperature in ℃
α = observed rotation in degrees
L = cell path length in decimetres (1 dm = 10 cm)
C = concentration (g / 100 ml)

12. A p p l i c a t i o n s 12
To determines product purity by measuring specific rotation and optical
rotation of: • Amino Acids
• Amino Sugars
• Antibiotics
• Dextrose
• Steroids
• Cocaine
• Diuretics
• Tranquilizers
• Analgesics
• Codeine
• Serums
• Vitamins
1
to measure the ratio of enantiomers in solutions.
Many optically active chemicals such as tartaric acid,
are stereoisomers, a polarimeter can be used to identify which isomer
is present in a sample --
2

13. 13
The optical rotation is proportional to the concentration of the substances
in solution.
-- to applied for concentration measurements of enantiomer-pure samples.
-- With a known concentration of a sample, polarimetry may also be
applied to determine the specific rotation (a physical property) when
characterizing a new substance.
-- if it rotates
polarized light to
the left, it is a
levo-isomer.
-- If it rotates
polarized light to
the right, it is a
dextro-isomer.
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14. References
1. https://www.kruess.com/en/campus/polarimetry/what-is-a-polarimeter/
2. https://www.chem.ucla.edu/~harding/tutorials/stereochem/calcs.html
3. http://www.inmetro.gov.br/inovacao/artigos/docs/128.pdf
4. http://www.iiserpune.ac.in/~bhasbapat/phy221_files/SITechPolar.pdf
5. https://rudolphresearch.com/products/polarimeters/polarimetry-
definitions/
6. https://www.slideshare.net/zzzggggggg/polarimetry-45019399
7. https://www.slideshare.net/raj_bhagwat/polarimetry-59864226
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15. Thank you 15