Christoph Johann | Authors


Developments in Field‑Flow Fractionation Coupled to Light Scattering

Field-flow fractionation (FFF) coupled to light scattering is a powerful method to separate and characterize nanoparticles, proteins, and polymers from a few nanometres to a few micrometres. The technique is one of the few that can cover the full size range of nanomaterials and provide high-resolution size distributions and additional characterization. New developments in FFF enhance performance and productivity.

Field-Flow Fractionation: Virtual Optimization for Versatile Separation Methods

Flow-field flow fractionation (flow-FFF) offers highly versatile separations for the analysis of complex fluids, covering a size range of macromolecules and particles from 1 nm to 10,000 nm. However, flow-FFF is often perceived as a difficult technique to learn because of the multiple parameters available for adjustment. Recent advances in software for simulating flow-FFF overcome this obstacle, enabling the virtual optimization of flow-FFF methods and opening up the power of flow-FFF separations to non-experts. An added benefit is the ability to easily analyze particle size distributions by elution time from first principles.

Asymmetric Flow Field Flow Fractionation: A Powerful Method for Polymer Characterization

Recent development of the instrumentation for asymmetric flow field flow fractionation (FFF) brings new possibilities for the characterization of synthetic and natural polymers with several advantages over traditionally used size exclusion chromatography (SEC). The main difference of asymmetric flow FFF compared to SEC is that the polymer separation takes place in an entirely empty channel, which eliminates undesirable SEC effects such as shearing degradation of polymers with ultra high molar mass, anchoring of branched macromolecules in SEC column packing, and enthalpic interactions of polymer molecules with a stationary phase.