Field-Flow Fractionation at 60 years: Where Are We Today and Where Are We Going?

Since its introduction in 19661, the field-flow fractionation (FFF) family of techniques has become recognized for its ability to address complex macromolecular and nanoparticle samples particularly those that span broad molecular weight or size distributions. The existing FFF theory that relates measured retention times to the analyte’s physicochemical properties, the ease of coupling FFF with on-line detectors that measure attributes of the eluting species as well as the ease of fraction collection for off-line analyses using orthogonal techniques have added important layers of insights into challenging sample systems.

Today, FFF, particularly asymmetrical flow FFF (AF4) is an integral part of the toolbox for analyses that include nanomedicine, nanoplastics, and polymers. This is attributed to developments on multiple fronts. First, commercial instrumentation has evolved with ease of use in mind. This includes less cumbersome FFF channel designs and software programs that help users select experimental conditions. Second, an increase in the number of publications describing applications and protocols that provide a framework for FFF procedures and methods, particularly for lipid-based nanoparticles and nano-objects2, have eased entry into FFF for users new to the technique. Third, new FFF analytical capabilities continue to be developed. While AF4 is the most well known of the FFF techniques, thermal FFF is the most intriguing, least understood, and presents new opportunities. The movement of macromolecules and nanoparticles in the presence of a temperature gradient forms the basis for new analytical capabilities such as composition and polymer architecture determinations.
This presentation will address the aforementioned points and advances in thermal FFF.