Methods for continuous flow fractionation of microparticles: Outlooks and fields of application

The development of new methods for fractionating particles of a different nature is becoming more important in solving some scientific and technological problems. This paper presents a brief review in the theory and practice of the most common techniques for microparticle fractionation (0.1–100 μm). These are dry and wet sieving, elutriation, sequential filtration, split-flow thin fractionation (SPLITT system), field-flow fractionation (FFF), membrane filtration, and capillary electrophoresis. Special attention is paid to the FFF technique, which offers a unique potential for the separation of different materials, from biopolymers and microorganisms to colloidal and solid particles, and the estimation of their physical properties. An alternative version of sedimentation FFF is described, namely, the fractionation of microparticles in rotating coiled columns. The main advantages and limitations of the methods are revealed and their outlooks and fields of applications are envisaged.