Specific rotation

Specific rotation is the standardized measure of a chiral compound’s optical activity: how much it rotates plane-polarized light, corrected for concentration and path length so that values can be compared. It identifies and quantifies optically active food components, most famously sugars, since a polarimeter reading reveals, for example, whether a syrup is still sucrose or has been inverted to glucose and fructose. Each pure compound has a characteristic specific rotation under defined conditions of wavelength, temperature, and solvent, which makes the measurement a classic tool for purity checking and for following reactions such as inversion and mutarotation.