sedimentation field-flow fractionation

SdFFF is a set of high resolution liquid chromatography-like elution methods used for sizing and separating colloidal matter into size fractions. SdFFF separations are performed within a flat open channel, usually having a rectangular cross-section and triangular end pieces where the sample and carrier fluid enters and leaves. The mechanism for particle separation involves only physical interactions. The sample is introduced into the channel through a septum or injection valve, and then the flow is turned off. A centrifugal field is then applied at right angles to the flat face of the ribbon-like channel. This flat channel sits within a centrifuge basket and the centrifugal field drives the particles towards the accumulation wall. There they form equilibrium clouds whose average thickness or elevation above the accumulation wall  depends on how strongly the particles interact with the field and also their diffusivity.