Understanding Field-Flow-Fractionation Theory

Field-Flow-Fractionation (FFF) is a one-phase chromatography technique invented by Professor Calvin Giddings in 1966. The Flow-FFF separation mechanism works based on hydrodynamic forces taking place in a separation channel. The smaller particles are transported faster along the channel than the larger particles and are eluting before the larger ones.

Flow-FFF is the most widely used variant within the family of FFF methods where high-resolution separation is achieved within a very thin flow against which a perpendicular force field is applied. Flow-FFF can be divided into two types of FFF variants:

Flow-FFF solves the most difficult separation, fractionation and sizing tasks in the macromolecular and colloidal arenas. The advantage of Flow-FFF over traditional SEC column chromatography is the ability to separate both soluable and colloidal components over a wide size range as well as sensitive and "sticky" samples (no stationary phase, no interaction). Its resolution is similar to sedimentation equilibrium, but it surpasses even this benchmark-sizing tool when one considers its flexibility, speed, and ease of use.

Flow-FFF is invaluable and indispensable in key areas of research and development in molecular biology, nanotechnology, and environmental analyses, including the separation and characterization of proteins and aggregates, liposomes, emulsions, viral particles, polysaccharides, nanoparticles, polymer latex particles, colloidal soil suspensions, humic substances, chemical mechanical polishing slurries (CMP), and many more.

Key Advantages

  • Separates both soluble and colloidal components over a wide size range; especially unmatched powers in sub-micrometer range
  • Large dynamic range: from a few nanometers to a few micrometers
  • Rapid analysis: typically 10 to 30 minutes
  • Absence of shearing forces (no stationary phase; separation takes part in separation channel)
  • Ultra-high resolution separations, comparable to ultra centrifugation
  • Simplifies analysis by eliminating many time-consuming sample preparation steps
  • Adjustable and flexible separation ability: very efficient for complex samples
  • Direct injection: minimal sample preparation necessary
  • Interfaces with modern analytical methods like MALS, MALDI-TOF, etc.
  • Fractions can be collected and used for off-line analysis (with electron microscopy, MS, ICP-MS, ELISA etc.)

Wyatt Technology's Eclipse® Flow-FFF separation system went to market in 2001 and has made an immediate impact in popularizing Flow-FFF. The fully automated, software controlled Eclipse® system uses only one pump to generate detector flow, cross flow and injection flow. This innovative concept to generate all three flow streams from one main flow has been a breakthrough for the Flow-FFF method.



Eclipse® DUALTEC:

  • Flat Channel (AF4) and Hollow Fiber (HF5) combined in one system
  • 2 inlet ports to channel (Tip Injection)
  • Software-controllable switching between AF4, HF5 and SEC mode
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Eclipse® AF4:

  • Flat Channel (AF4), Frit-Inlet Channel (FI-AF4) and Semi-Prep (SP2) Channel available
  • 3 inlet ports to channel (central down-stream injection)
  • Metall-free Option available
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Flow-FFF Separation using Wyatt Technology's Eclipse® AF4:

How Flow-FFF Separation Works: