Fine-particle separation and characterization by field-flow fractionation

Abstract

Summary Field-flow fractionation (FFF) is described as a one-phase form of chromatography and its advantages are summarized. Its applicability to colloids and fine particles is considered. A brief discussion of FFF principles and theory is focused on retention and plate height, pointing to the unique fact that in FFF increased retention leads to a considerable decrease in plate height. Two sub-techniques, sedimentation FFF and flow FFF, are discussed at length because they have shown the greatest promise for particle separation and characterization. Examples of the former are presented, showing that mass and diameter information can be extracted directly from the fractogram. Attention is also given to the consistency of results within the sedimentation FFF system. It is shown that variations in field strength and flow-rate can be used to control retention and resolution. These controls demonstrate the flexibility of the system with respect to analysis time and resolving power. In a brief discussion of flow FFF the remarkable mass range capability of this sub-technique is noted.