How do I resuspend the particles?
Microparticles with diameters greater than about 0.4 micron tend to settle upon prolonged storage, because the Brownian motion of the particles in the fluid is not sufficient to overcome the constant pull of gravity. If particles have settled, they may be resuspended by swirling or rolling the container, or by sonication. Agitation strong enough to produce foam should be avoided. Polystyrene microparticles with diameters over 0.6 micron should be resuspended monthly to prevent irreversible aggregation.
