Development of continuous two-dimensional asymmetrical flow field-flow fractionation for particles: Principle, instrument development and applications

Continuous two-dimensional field-flow fractionation (2D-FFF) is a field flow fractionation principle for continuous fractionation of macromolecules and particles [1]. In this technique the separation occur in a thin disc-shaped channel, where a carrier liquid flows radially from the center towards the perimeter of the channel, and a steady stream of the sample solution is introduced continuously at a second inlet close to the center. Under influence of the field, the sample components are separated in radial direction according to the analytical FFF principle. Simultaneously, the lower channel wall is rotating with respect to the stationary upper wall, while a shear-driven flow profile deflects the separated sample components into continuous trajectories that strike off at different angles over the 2D surface. Finally, the sample components are collected at the outer rim of the channel. In this work a new 2D-FFF instrument design with asymmetrical cross flow as a force field was constructed according to the principles of AF4 and the continuous 2D-FFF. Instrument performance was tested using coloured samples. The effect of different flow parameters on fractionation was investigated.