The most important parameter for light-scattering measurements in the Rayleigh scattering region is the Rayleigh ratio, which is necessary to obtain the absolute scattered light intensity from the relative scattered light intensity. The absolute scattered light intensity is directly related to the molar masses of polymers, colloids, biomolecules, and the like. A new Rayleigh ratio was determined by measuring static light scattering from certified reference materials with highly accurate certified values of the molecular weight determined by several other techniques, such as MALDI-TOF mass spectrometry or size-exclusion chromatography. The new Rayleigh ratio can be used for evaluating the uncertainty of the molecular weight of polymers and macromolecules, as measured by light scattering.
Keywords: Rayleigh ratio; molecular weight; polystyrene; reference material; static light scattering; uncertainty.