Observed Rotation
Definition
Observed rotation is the angle measured in an optical-rotation examination under the stated sample and instrument conditions. Path length, composition, concentration and other relevant conditions affect the result, which is distinct from a normalised specific rotation or enantiomeric excess.
- Context
- Optical rotation
For example, the same optically active material can produce different measured angles when path length or other relevant conditions change.
A complex mixture’s measured rotation cannot automatically provide one compound’s purity or enantiomeric excess. Other optically active substances and conditions can contribute.
Related terms
- Enantiomeric Excess
- Enantiomeric excess describes the relative excess of one member of an enantiomeric pair over the other under a stated composition convention. It...
- Saccharimeter
- A saccharimeter is a polarimetric instrument that reports optical rotation using a specified sugar-related scale or convention. Its interpretation depends on the...
- Specific Rotation
- Specific rotation is an optical-rotation quantity normalised under a stated path-length and concentration convention, with relevant measurement conditions specified. Comparing values requires...
Explained in
- Polarimetry and Optical Rotation in Forensic AnalysisMeasured angle under the stated sample and instrument conditions.