A Lab Tool for Sugar: The Optical Rotatory Dispersion of d-Glucose from Its Mutarotation Kinetics with a Home-Made Polarimeter

A polarimeter constructed from off-the-shelf parts was used to measure the optical rotation of sugars as the central activity in a second-year online analytical chemistry laboratory course. Throughout the five-weeks of the course, students built the instrument and performed measurements of sugars at three different wavelengths. The kinetics for the mutarotation of glucose was measured, and its equilibrium constant was used to determine the optical rotatory dispersion of pure α- and β-d-glucose in solution, via linearization of Drude’s equation. This activity serves as a foundation of instrument construction and calibration, data analysis, and error propagation in optical measurements, while connecting concepts of introductory, organic, and physical chemistry in an experimental setting.