General Theory about Field-Flow Fractionation
The Field-Flow Fractionation Principle
Field-Flow Fractionation is a family of separation techniques, comprising of various different sub-techniques. All these Field-Flow Fractionation versions utilize the same basic separation principle, but employ different force fields. Depending on the used separation field the technique is called Flow Field-Flow Fractionation, Sedimentation Field-Flow Fractionation, Thermal Field-Flow Fractionation or Split Flow Thin Cell Fractionation (SPLITT). Field-Flow Fractionation is providing fast, gentle and high resolution separations of any particulate matter from 1 nm up to 100 µm in a liquid medium. The sample is separated inside an open flow channel without the presence of any packing or stationary phase inside.
Different separation forces
Depending on the Field-Flow Fractionation method which is used, different force fields (liquid flows, centrifugal forces, temperature gradients or gravity fields) are used and applied perpendicular to the separation channel. Under the influence of these force fields and the counteracting diffusion field, different equilibrium layers are formed by the sample analytes. Smaller particles are located in faster and bigger particles are located in slower stream lines of the laminar flow inside the channel. This results in the elution pattern where smaller particles are transported faster through the channel than the bigger ones.
History: Prof Calvin Giddings, the FFF Inventor
Field-Flow Fractionation was invented and patented in 1966 by Prof. Calvin Giddings (1930-1996), an outstanding scientist and two-times Nobel-Price nominee (1984/1994), from University Utah at Salt Lake City, USA. Prof. Giddings founded the Field-Flow Fractionation Research Center (FFFresearch Center) at University of Utah, where he developed the complete theory of Field-Flow Fractionation and the different Field-Flow Fractionation sub-techniques. Prof. Giddings and his team developed Thermal Field-Flow Fractionation in 1969, Sedimentation Field-Flow Fractionation in 1974, Flow Field-Flow Fractionation in 1976 and Split Flow Thin Cell Fractionation (SPLITT) in 1985. In 1987 Giddings/Wahlund published the first paper about Asymmetric Flow Field-Flow Fractionation, which revolutionized Flow Field-Flow Fractionation and later became the most popular Field-Flow Fractionation technology used today.
History: Prof. Michel Martin, first coupling to Light-Scattering
Another important step in the evolution of the Field-Flow Fractionation technology was achieved, when Prof. Michel Martin from École Supérieure de Physique et de Chimie Industrielles in Paris first postulated and finally in 1984 published the World’s First Online Coupling of Field-Flow Fractionation with Light Scattering. Combining the separation power of Field-Flow Fractionation with the particle sizing power of Light Scattering creates an unmatched high resolution particle sizing tool without comparison. This visionary work of Prof. Martin formed the basis of today’s modern Field-Flow Fractionation – Light Scattering technology. Several other groups copied this approach, by using the broad instrumental FFF basis developed by Prof. Giddings and his team.
In 1986, Prof. Giddings and some co-workers founded the legendary company FFFractionation, Inc. in Salt Lake City. It was the first company in the field of Field-Flow Fractionation, which developed and introduced the world’s first commercial Field-Flow Fractionation instruments, the Models T100 (Thermal Field-Flow Fractionation), S101 (Sedimentation Field-Flow Fractionation), F1000 (Flow Field-Flow Fractionation) and SF1000 SPLITT (Split Flow Thin Cell Fractionation).