Field Flow Fractionation in Analysis of Polymers and Rubbers

Abstract

Field‐flow fractionation (FFF) was conceived by J. Calvin Giddings in 1966 as a separation and characterization method for macromolecules, colloids, and particulates. Like chromatography, sample migration is caused by differential interaction with a field acting along an axis orthogonal to that of the transport liquid. Unlike chromatography, where separation is achieved by solutes partitioning between mobile and stationary phases, separation in FFF arises from the distribution of sample components in fluid laminae flowing at different velocities in a single phase. The different flow velocities, described by a parabolic profile, arise from the high aspect ratio of the FFF channel. Different types of fields can be used in FFF as long as they interact with some physicochemical property of the sample. The FFF channel design makes it highly suited for analyses of fragile aggregates, high‐molecular‐weight polymers, and gels. In comparison with packed columns, shear rates in the channel and the probability of plugging the channel are low. The ability of thermal FFF to differentiate polymers and latexes of different bulk and surface composition is unique among currently used separation techniques. The FFF family of techniques can provide a great deal of information about the sample but an initial time investment is often required for methods development. In this article, the fundamental mechanism of FFF is shown at play in the separation and characterization of polymers and rubbers by the two techniques par excellence in this field: flow FFF and thermal FFF.

Widening the Therapeutic Perspectives of Clofazimine by Its Loading in Sulfobutylether β-Cyclodextrin Nanocarriers: Nanomolar IC50 Values against MDR S. epidermidis

“…Regenerated cellulose membranes with a 10 kDa cutoff (Microdyn-Nadir, Wiesbaden, Germany) were used. An AF4 method is composed of four steps: focus, focus–injection, elution, and elution–injection . During the focusing step, two opposite flows of carrier fluid equilibrate (focus) and confine the injected sample (focus–injection) in a narrow band, allowing the analytes to penetrate the flow profile according to their diffusion coefficient; the sum of these flows is the focus flow, which exits from the membrane and is then directed to waste.…”

Chip-Type Asymmetrical Flow Field-Flow Fractionation Channel Coupled with Mass Spectrometry for Top-Down Protein Identification

“…Flow field-flow fractionation (flow FFF or F4), a variant of the FFF methods, is an elution technique for the separation of macromolecules or particulate species and has gained increasing interest as a size fractionation method for large biomolecules such as proteins, nanometer- to micrometer-sized subcellular species, cells, and natural aqueous polymers. − Separation by F4 takes place in an unobstructed channel space with a rectangular cross-section or in a hollow fiber (HF) membrane (HF-flow FFF or HF5) with a circular cross-section , and is achieved by the interaction of two independent flow streams, a migration flow moving along the channel axis and a crossflow (for rectangular channels) or radial flow (for HF) acting on the channel wall perpendicular to the channel axis. The size-sorting capability of F4 separation results from the differential migration of sample species depending on different diffusion rates (inversely proportional to the hydrodynamic size of the sample component) against the crossflow force acting on the channel wall, in which faster diffusing molecules (smaller size) travel further from the channel wall than do larger ones.…”

Flow field‐flow fractionation with chemiluminescence detection for flow‐assisted, multianalyte assays in heterogeneous phase

“…Elution order is from larger to smaller PS size, as expected for steric/hyperlayer (st/hyp) FlFFF [11,15,16]. The specificity of CL detection is clearly apparent when it is compared to UV/Vis detection, because peaks due to uncoated PS are not present in the CL fractogram.…”

“…Phone/Fax: +39 051 343398. E-mail: aldo.roda@unibo.it nalyte assays can take advantage of the ability of Flow FFF (FlFFF) to separate mixtures of micrometer-sized particles coated by different analytes at higher size-based selectivity and shorter analysis time than in GrFFF [11].…”