Polarimetry

Polarimetry Presentations

1. A SEMINAR ON POLARIMETRY By BHAVANI.G 14y66s0402 VIJAYA COLLEGE OF PHARMACY Munaganoor (v), Hayathnagar , HYD.

2. Introduction The term Polarimetry may be referred as the study of the rotation of polarised light by transparent optically active substance. This is a type of qualitative and quantitative analytical technique as both identification and estimation of the compound can be done.

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

4. The optically· active substances are of two types:  ( i )   Dextro rotatory or right handed.  The substance which rotates plane of polarization of light towards right or in clockwise Direction are called dextro rotatory or right handed. (ii) Laevo rotatory or left handed.  The substance which rotates plane of polarization of light towards left or in anti-clockwise directions are called laevo rotatory or left handed. Ex: Lactic acid

5. Instrumentation A polarimeter consists of a polarized Light source – Sodium vapor lamp, Polarizer – quartz prism material and Analyzer – Nicol prism aligned to intercept the linearly polarized ray as it emerges from the sample solution, a graduated circle- to measure the rotation angle, and sample tubes.

6. Applications Identification Determination of Optically active compounds Optical activity is the only one parameter, for distinguishing b/w D & L isomeric forms. Chemical industry: Many chemicals exhibit a specific rotation as a unique property (like refractive index in many cases) which can be used to distinguish it.

7. Food, beverage and pharmaceutical industries: Concentration and purity measurements are done to those Samples that display specific rotations that can be calculated for purity with a polarimeter include: Steroids,Diuretics,Antibiotics,Narcotics,Vitamins,Analgesics,AminoAcids,EssentialOils,Polymers,Starches,Sugars . Sugar industry: Polarimeters are used in the sugar industry for determining quality of both juice from sugar cane and the refined sucrose. Often, the sugar refineries use a modified polarimeter with a flow cell called a saccharimeter. Polarimetry of thin films and surfaces is commonly known as ellipsometry .

8. Polarimetry is used in remote sensing applications, such as planetary science and weather radar. Polarimetry can be used to measure various optical properties of a material, including linear birefringence, circular birefringence (also known as optical rotation (or) optical rotary dispersion), Dichroismlinear dichroism , circular dichroism and scattering.

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