Polarimeter

Overview

Source: Vy M. Dong and Diane Le, Department of Chemistry, University of California, Irvine, CA

This experiment will demonstrate the use of a polarimeter, which is an instrument used to determine the optical rotation of a sample. Optical rotation is the degree to which a sample will rotate polarized light. Optically active samples will rotate the plane of light clockwise (dextrorotatory), designated as d or (+), or counterclockwise (levorotatory), designated as l or (−).

Procedure

1. Preparing the Polarimeter

Turn on instrument and let it warm up for 10 min.
Make sure instrument is set to "optical rotation" mode.
Prepare a blank sample in the polarimeter cell (1.5 mL total sample volume, 1 dm in length) containing only CHCl₃. Make sure there are no air bubbles present.
Place the blank cell in the holder and press "zero."

2. Preparation of Analyte Sample

Prepare a stock solution of 10

Results

Representative results for the measurement and calculation of specific rotation for Procedures 1-4.

Procedure Step	Reading on polarimeter
1.4	0.000
3.2	+0.563
4.1	[α]₂₅^D = +77° (c 0.73, CHCl₃) Log in or to access full content. Learn more about your institution’s access to JoVE content here Application and Summary In this experiment, we have demonstrated the principles behind the polarimeter and how to measure and calculate the specific rotation of an optically active compound. The polarimeter is an important instrument in the fine-chemical and pharmaceutical industries to assess the identity, purity, and quality of a compound. It is specifically used for the measurement of optical rotation of chiral compounds, which can be used to distinguish the identity of two enantiomers by confirming whether it is Log in or to access full content. Learn more about your institution’s access to JoVE content here Tags Polarimeter Purity Assessment Chemical Properties Enantiomers Mirror image Variants Biological Activities Pharmaceuticals Drug Thalidomide Principles Of Polarimetry Setup And Operation Applications Organic Compounds Stereocenters Chiral Compounds Mirror image Isomers Enantiomers Physical Properties Optics Skip to... 0:00 Overview 0:49 Principles of Polarimetry 3:51 Initialization of the Polarimeter 4:24 Calibration and Measurement 5:23 Applications 6:52 Summary Videos from this collection: Now Playing Polarimeter Organic Chemistry II 97.9K Views Cleaning Glassware Organic Chemistry II 120.8K Views Nucleophilic Substitution Organic Chemistry II 97.8K Views Reducing Agents Organic Chemistry II 42.5K Views Grignard Reaction Organic Chemistry II 147.6K Views <em>n</em>-Butyllithium Titration Organic Chemistry II 46.9K Views Dean-Stark Trap Organic Chemistry II 97.1K Views Ozonolysis of Alkenes Organic Chemistry II 66.1K Views Organocatalysis Organic Chemistry II 16.3K Views Palladium-Catalyzed Cross Coupling Organic Chemistry II 33.2K Views Solid Phase Synthesis Organic Chemistry II 40.0K Views Hydrogenation Organic Chemistry II 48.0K Views Polymerization Organic Chemistry II 89.7K Views Melting Point Organic Chemistry II 145.2K Views Infrared Spectroscopy Organic Chemistry II 205.1K Views Privacy Terms of Use Policies Contact Us Recommend to library JoVE NEWSLETTERS Research JoVE Journal Methods Collections JoVE Encyclopedia of Experiments Archive Education JoVE Core JoVE Business JoVE Science Education JoVE Lab Manual Faculty Resource Center Faculty Site Authors Overview Publishing Process Editorial Board Scope and Policies Peer Review FAQ Submit Librarians Overview Testimonials Subscriptions Access Resources Library Advisory Board FAQ ABOUT JoVE Overview Leadership Blog JoVE Help Center Copyright © 2025 MyJoVE Corporation. All rights reserved