Definition
Optical rotation refers to the rotation of the plane of polarization of polarized light as it passes through an optically active substance. It is quantified as:
where:
α is the observed rotation (degrees).
[α] is the specific rotation (degrees·dm⁻¹·g⁻¹·mL).
l is the path length of the sample (dm).
ccc is the concentration (g/mL).
Determination
Polarimeter: The primary instrument used to measure optical rotation. A sample is placed in a polarimeter tube, and the angle of rotation is measured as polarized light passes through it.
Applications of Optical Rotation:
Pharmaceuticals: Determining the concentration and purity of chiral drugs.
Food Industry: Measuring the sugar content in solutions.
Chemical Analysis: Identifying and characterizing chiral compounds.
