Separation and characterization of colloidal materials of variable particle size and composition by coupled column sedimentation field-flow fractionation

Abstract

Coupled column field-flow fractionation (FFF), In which a narrow fraction collected from one run is reinjected for a second FFF run under different conditions, Is shown to be a multidimensional technique analogous to coupled column chromatography. By using different carrier densities In successive sedimentation FFF stages, this approach Is theoretically capable of unraveling both the size and density characteristics of the components of complex colloids. This concept Is tested here by preparing simple binary mixtures of polystyrene (PS) and poly(vinyl chloride) (PVC) latex particles; coupled column FFF is then used to recover size and density Information on the PS latex despite the presence of the PVC "contaminant". The problem of transferring enough of a sample fraction from the first stage to the second to provide an adequate detector signal Is approached by three concentration methods: split-outlet concentration, on-channel concentration, and centrifugation. All work reasonably well, but Improvements In some of these techniques would greatly simplify the practical usage of coupled column FFF.

A Method for the High Performance Gel Filtration Chromatography Characterization of Inorganic Colloids

“…Small-angle X-ray scattering and small-angle neutron scattering have been used to determine particle size distributions in colloids, but the inaccessibility of these techniques limits their usage (15,16). Field-flow fractionation has been used to find size distributions of colloidal particles, but experimental difficulties still limit its application (17). For example, it requires extensive analysis time and large mobile phase volumes.…”

Accurate Measurement of Density of Colloidal Latex Particles by Sedimentation Field-Flow Fractionation

“…The plotting procedure was later modified to accommodate runs made at different field strengths (different rpms). 27 In the plotting procedure referred to above, the carrier density is plotted against experimental retention and field strength data such that a straight line is generated. The slope of the line yields particle diameter.…”