synonyms: BFFF mode, NFFF mode, normal FFF, normal FFF mode (NFFF)
initialism: BFFF
https://doi.org/10.1351/goldbook.09932
Mechanism of field-flow fractionation of sub-micron particles that relies on Brownian motion.
Notes:
- BFFF mode requires a specific sample injection procedure described as stop-flow injection or a relaxation step. A relaxation time is needed to equilibrate the sample under the influence of a force field and Brownian diffusion in the absence of flow. The injected sample is forced to concentrate in a thin layer adjacent to the accumulation wall (channel bottom).
- When the flow is switched on, elution begins with smaller particles, which are distributed further away from the accumulation wall and thus protrude further into the faster flow streams; larger particles elute later.
- Two main factors influencing the sample behaviour in BFFF mode are the properties of particles characterized by the diffusion coefficient and the strength of the cross-field applied.