Colloid characterization by sedimentation field-flow fractionation. IV. Reinjection field-flow fractionation for polydisperse systems

Abstract

It is shown that some of the colloidal properties (particle mass, diameter, density, etc.) which can be measured by sedimentation field-flow fractionation (FFF) for monodisperse colloidal fractions are obscured for polydisperse samples because of the fractionation process. Reinjection of FFF, in which narrow fractions are cut from the first FFF run and reinjected for a second run, is proposed as a method to remedy this difficulty and generally to expand the base of measurable properties for polydisperse colloids. Accordingly, the theoretical basis of reinjection FFF is developed. Experiments with a polydisperse polyvinyl chloride latex are performed to demonstrate the experimental feasibility of the method.