Polarimetry is a technique that measures the rotation of polarized light after it passes through an optically active compound. It involves using a polarimeter instrument containing a light source, polarizer, sample tube containing the compound, and analyzer. The technique is used to quantify concentration and qualitatively distinguish between isomers by measuring their specific rotation values. It has applications in pharmaceutical, chemical, food, and other industries for quality control and research.

1. POLARIMETRY
PRESENTED BY
PATAN BASHA
B – PHARM ( PHARMACIST )

2. CONTENTS
 INTRODUCTION
 PLANE POLARISED LIGHT
 OPTICALACTIVITY
 THEORY OF OPTICALACTIVITY
 POLARIMETER
 APPLICATIONS

3. INTRODUCTION
POLARIMETRY IS ONE OF THE IMPORTANT
INSTRUMENTAL METHODS EMPLOYED IN ANALYSIS.
THIS MEASURES THE ROTATION OF THE POLARIZED
LIGHT AS IT PASSES THROUGH AN OPTICALLY
ACTIVE COMPOUND.
THIS TECHNIQUE INVOLVES THE MEASUREMENT OF
CHANGE IN THE DIRECTION 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.

4. PLANE POLARISED LIGHT
AS PER 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.
NICOL PRISM – ICELAND SPAR
 CALCITE ( CACO3 FORM )
 POLAROID

7. OPTICAL ACTIVITY
 OPTICAL ACTIVITY: THE COMPOUNDS WHICH ARE HAVING THE
ABILITY TO ROTATE THE PLANE OF POLARISED LIGHT ARE CALLED
OPTICALLY ACTIVE COMPOUNDS.
 THIS PROPERTY OF COMPOUNDS IS CALLED OPTICALACTIVITY
 THE ROTATORY POWER OF A GIVEN SOLUTION IS GENERALLY
EXPRESSED AS SPECIFIC ROTATION
 MAGNITUDE OF ROTATION DEPEND UPON
 NATURE OF SUBSTANCE
 LENGTH OF LIQUID COLUMN (L)
 CONCENTRATION OF THE SOLUTION (1GM /100ML)
 NATURE OF THE SOLVENT
 TEMPERATURE OF THE SOLUTION (T)
 WAVELENGTH OF THE LIGHT USED

8. SPECIFIC ROTATION
THE ROTATORY POWER OF A GIVEN SOLUTION IS
GENERALLY EXPRESSED AS SPECIFIC ROTATION
IT IS THE NUMBER OF DEGRESS OF ROTATION OF PLANE
POLARIZED LIGHT PRODUCED BY ONE GRAM OF THE
SUBSTANCE PER ML.
MEASUREMENTS IS CARRIED OUT AT TEMP USING
SODIUM LIGHT.
[α] = specific rotation, T = temperature,
λ = wavelength, θ= optical rotation,
c = concentration in g/100ml, l = optical path length in dm.

9. TYPES OF MOLECULES ANALYSED
POLARIMETRY
MOLECULE MUST BE OPTICALLY ACTIVE
OPTICALLY ACTIVE MOLECULE CONTAIN ASYMMETRIC CARBON
E.G: SUGAR, NUCLEIC ACID, AMINO ACID
CH3
Cl
H OH

10. NEGATIVE VALUE MEANS LEVOROTATORY
POSITIVE VALUE MEANS DEXTROROTATORY
GLUCOSE +52.70
SUCROSE +66.47O
PENICILLIN V +223O
CAMPHOR +44.26O
CHOLESTEROL -31.5O
FRUCTOSE -92.00
MORPHINE -132.00
L-PROLINE -84.00

11. INSTRUMENTATION
OPTICAL ACTIVITY MAY BE DETECTED & MEASURED BY AN
INSTRUMENT → POLARIMETER

13. LIGHT SOURCE – SODIUM VAPOR LAMP
POLARIZER –QUARTZ PRISM CONVERT UNPOLARIZED LIGHT
INTO PLANE POLARIZED LIGHT
SAMPLE TUBE: CONTAINS SAMPLE TO BE ANALYSED (GLASS. 10
CM LENGTH)
ANALYZER - NICOL PRISM ALIGNED TO INTERCEPT THE
LINEARLY POLARIZED RAY AS IT EMERGES FROM THE SAMPLE
SOLUTION
GRADUATED CIRCLE- TO MEASURE THE ROTATION ANGLE,
AND SAMPLE TUBES.

15. Jasco-p-2000-digital-polarimeter

16. APPLICATIONS
QUANTITATIVE APPLICATION
• IF THE SPECIFIC ROTATION OF SAMPLE IS KNOWN ITS
CONCENTRATION IN THE SOLUTION CAN BE ESTIMATED
QUALITATIVE APPLICATION
OPTICAL ACTIVITY IS THE ONLY PARAMETER AVAILABLE
FOR DISTINGUISHING BETWEEN D AND L ISOMERIC FORMS
SACCHARIMETRY
 IMPORTANT PRACTICAL APPLICATION OF POLARIMETRY
 DETERMINATION OF HIGH CONC. OF SUGARS
 VISUAL SACCHARIMETERS CALLED POLAROSCOPES

17. APPLICATIONS
IT IS EMPLOYED IN QUALITY CONTROL, PROCESS CONTROL
AND RESEARCH IN THE PHARMACEUTICAL, CHEMICAL,
ESSENTIAL OIL, FLAVOR AND FOOD INDUSTRIES
PHYSICAL PROPERTY
DISTINGUISHING BETWEEN OPTICAL ISOMERS
ANALYZING MOLECULAR STRUCTURE BY PLOTTING OPTICAL
ROTATORY DISPERSION (ORD) CURVES
INVESTIGATING KINETIC REACTIONS BY MEASURING OPTICAL
ROTATION AS A FUNCTION OF TIME