Polarimetry and Circular Dichroism

Polarimetry and Circular DichroismThe Polarimetry and Circular Dichroism (CD) Spectroscopy Services are analytical facilities based in the Department of Chemistry and are offered to all University of Sheffield departments as well as external customers.

Polarimetry

Facility 1

A polarimeter is used to measure specific rotation which is a measure of the ability of optically active or ‘chiral’ compounds to rotate the plane of monochromatic plane-polarised light.

This value can be used in the prediction of enantiomeric excess. Minimum sample size is usually 20mg’s but may be more depending on the required analysis.

Samples are analysed in solution (or as neat liquids) in one of the range of cells available. Wavelength, temperature, solvent and concentration are all relevant to a specific rotation and should always be noted.

Traditionally the wavelength of 589nm (Sodium D-line) is used but more sensitivity may be obtained using 546nm (Mercury E-line).

Circular Dichroism (CD) Spectroscopy

Facility 2

Circular dichroism may be observed in optically active or ‘chiral’ materials when they absorb left and right handed circularly polarised light slightly differently.

Measured using a CD Spectropolarimeter, a CD spectrum shows this difference in absorbance as a function of wavelength.

University of Sheffield customers should bring their samples along with a completed Internal service form and purchase order form (members of the Department of Chemistry do not need a purchase order form) to lab C43 in the Dainton Building (turn left in the main entrance and follow the corridor around to the right).

External customers should send their samples along with a completed external service form and purchase order form to: Robert Hanson, Department of Chemistry, University of Sheffield, Dainton Building, Sheffield S3 7HF, UK

Please contact Rob Hanson to discuss your requirements, costings and turnaround time.

Contact: Rob Hanson, r.j.hanson@sheffield.ac.uk