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Difference between revisions of "Field-Flow fractionation (FFF)"
Field-Flow fractionation (FFF) (view source)
Revision as of 14:13, 31 January 2022
, 14:13, 31 January 2022→Asymmetric flow FFF (AF4)
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| Product = Biomass in different physicochemical fractions | | Product = Biomass in different physicochemical fractions | ||
|Name=Field-Flow fractionation}} | |Name=Field-Flow fractionation}} | ||
<onlyinclude>'''Field-Flow Fractionation (FFF)''' is a separation | <onlyinclude>'''Field-Flow Fractionation (FFF)''' is a class of analytical methods suitable for the separation and characterization of nanomaterials, and shares the most common likeness with liquid [[chromatography]] (LC). The mechanism for separation, however, does not involve interactions with a stationary phase used in LC methods. Instead, a field is applied normal to a laminar flow through a narrow channel, which reslts in a parabolic flow profile, separating different analytes into distinct regions of the velocity profile. The analytes can be fractionated according to their physicochemical properties such as charge, chemical composition, density, molar mass, and size. Beside analytical purposes the FFF can also be utilised for preparative purposes.</onlyinclude> | ||
==Feedstock== | ==Feedstock== | ||
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[[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 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.<ref>{{Cite book|author=Robert I. MacCuspie|year=2018|section_title=Characterization of Nanomaterials for NanoEHS Studies|book_title=Nanotechnology Environmental Health and Safety|publisher=William Andrew}}</ref> 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).<ref>{{Cite book|author=P. Senthil Kumar, K. Grace Pavithra, Mu. Naushad|year=2019|section_title=Characterization techniques for nanomaterials|book_title=Nanomaterials for Solar Cell Applications|publisher=Elsevier}}</ref> | 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.<ref>{{Cite book|author=Robert I. MacCuspie|year=2018|section_title=Characterization of Nanomaterials for NanoEHS Studies|book_title=Nanotechnology Environmental Health and Safety|publisher=William Andrew}}</ref> AF4 can be coupled with downstream detectors to obtain complementary data, which includes UV-vis spectra from diode array detectors, refractive index measurements, multiangel light scattering, or inductively coupled plasma mass spectroscopy (ICP-MS).<ref>{{Cite book|author=P. Senthil Kumar, K. Grace Pavithra, Mu. Naushad|year=2019|section_title=Characterization techniques for nanomaterials|book_title=Nanomaterials for Solar Cell Applications|publisher=Elsevier}}</ref> | ||
=== Centrifugal FFF === | === Centrifugal FFF === | ||