What is static light scattering (SLS)?

Static light scattering (SLS) is a technique that measures the average scattering intensities to calculate the weight-average molecular weight of particles in a liquid solution. When a laser beam irradiates macromolecules in solution, the macromolecules scatter light in all directions.

The relationship between the scattering intensity and the molecular weight of a macromolecule is described by the simplified Rayleigh equation:

The instrument collects scattering intensities of macromolecules in solutions at different sample concentrations. The Debye plot is then constructed by plotting and linearly fitting the Kc/R_θ values versus the concentrations. The slope of the linear fit is used to calculate the second virial coefficient A₂. And the Y-axis intercept of the linear fitting yields the reciprocal of molecular weight.

Struggling to grasp particle analysis concepts? Our new Beginner's Guide to Particle Analysis is here to help you grasp these concepts in the most accessible manner possible. Download it as a PDF to read on the train, on the plane, or wherever else there’s no internet.