New Methodologies of Field-Flow Fractionation for The Separation and Characterization of Dilute Colloidal Samples

Abstract

Abstract New methodologies of conventional sedimentation Field-Flow Fractionation (SdFFF), potential barrier sedimentation Field-Flow Fractionation (PBSdFFF) and potential barrier gravitational Field-Flow Fractionation (PBGFFF) for the separation and characterization of dilute monodisperse or polydisperse, submicron or supramicron, colloidal samples are presented in this work. Both the conventional and potential barrier methodologies of Field-Flow Fractionation (FFF) are based on the “adhesion” of the dilute colloidal samples at the beginning of the channel wall followed by their total removal and analysis. In the conventional SdFFF concentration procedure the “apparent adhesion” of a dilute sample is due to its strong retention, which can be achieved by applying high field strengths and low flow rates. In Potential Barrier Field-Flow Fractionation (PBFFF) concentration procedures, the “true adhesion” of a dilute colloidal sample is attributed to its reverse adsorption at the beginning of the column, which can be achieved by the appropriate adjustment of various parameters influencing the interactions between the colloidal particles and the channel wall material. The total release of the adherent particles is accomplished either by reducing the field strength and increasing the solvent velocity (conventional SdFFF concentration procedure) or by varying the potential energy of interaction between the colloidal particles and the column material, for instance, by changing the ionic strength of the carrier solution (potential barrier FFF concentration procedures).