257
edits
Difference between revisions of "Field-Flow fractionation (FFF)"
Jump to navigation
Jump to search
m
Field-Flow fractionation (FFF) (view source)
Revision as of 13:38, 31 January 2022
, 13:38, 31 January 2022→Asymmetric flow FFF (AF4)
Lars Krause (talk | contribs) |
Bas Davidis (talk | contribs) |
||
| Line 25: | Line 25: | ||
[[File:AFFFF channel.svg|thumb|Illustration of a separation channel for asymmetric flow field-flow-fractionation.]] | [[File:AFFFF channel.svg|thumb|Illustration of a separation channel for asymmetric flow field-flow-fractionation.]] | ||
[[File:FFF Separation Mechanism.webm|thumb|Animation of the AF4 separation driven by particle diffusion in a parabolic flow profile. Particles colored in red are the smaller and particles colored in blue are the larger ones. The force applied on the top is the crossflow (indicated by the arrows on the bottom). The elution flow in longitudinal direction is shown with the flow arrows indicating the velocity profile.]] | [[File:FFF Separation Mechanism.webm|thumb|Animation of the AF4 separation driven by particle diffusion in a parabolic flow profile. Particles colored in red are the smaller and particles colored in blue are the larger ones. The force applied on the top is the crossflow (indicated by the arrows on the bottom). The elution flow in longitudinal direction is shown with the flow arrows indicating the velocity profile.]] | ||
The asymmetric flow FFF (AF4) is realised in a separation channel where | The asymmetric flow FFF (AF4) is realised in a separation channel where a separation force is generated in the form of an asymmetric crossflow through a semipermeable membrane and frit. The introduction of the crossflow through the semipermeable membrane holds the macromolecules back, and consequently, they get pushed against the membrane. The macromolecules move back into the channel from the accumulation membrane due to Brownian motion or normal diffusion. Diffusion is a size-dependent phenomenon. Hence, small molecules get access to high flow velocity solvent streams situated closer to the center of the parabolic flow profile. Consequently, macromolecules elute in order of increasing size. AF4 can be coupled with downstream detectors, which includes UV-vis spectra from diode array detectors, refractive index measurements, multiangel light scattering, or inductively coupled plasma mass spectroscopy (ICP-MS). | ||
=== Centrifugal FFF === | === Centrifugal FFF === | ||