size exclusion chromatography
The core principle of size exclusion chromatography (SEC) is to create a high gradient of diffusion coefficients for particles of different sizes. Small particles will diffuse slower than bigger particles (contrary to brownian diffusion). If a column is made, and one collects what comes down, the size of the particles will depend on the time of collection.
iZon sells some beads that induce this different diffusion coefficient, and a tool that automatically spins at given intervals in order to collect the sample that falls through at precise intervals.
I assume the same principle would work for charged particles under an electrical field, for example. Perhaps it is not so different from what gel electrophoresis does, but without involving a gel and therefore having a much cleaner resulting sample?
I wonder why the name chromatography if it does not involve color at all. Perhaps historical reasons?