Simultaneous determination of particle size and density in polydisperse colloidal samples by sedimentation field-flow fractionation

Sedimentation Field-Flow Fractionation (SFFF), which is a one-phase chromatographic system, is shown to be a rapid and convenient method for the simultaneous determination of particle size and density in polydisperse colloidal samples. This can be done by a methodology based on the variation of the carrier solution density using various aqueous glycerol solutions having different concentrations. A polydisperse polyvinyl chloride (PVC) latex sample was used as a model colloid. The average diameters and densities found by the proposed methodology are in good agreement with those obtained from the normal. SFFF procedure using a carrier of constant density or given by the manufacturer. Number average, d_N, and weight average, d_w, particle diameters were determined for the PVC sample at various carrier solutions containing glycerol up to 40 % (w/w) in order to show whether sample aggregation has occurred or not in the presence of glycerol. In all cases, the ratio d_w/d_N was found to be constant, showing that PVC aggregation has not occurred. Therefore our results, obtained by the proposed methodology in SFFF, are accurate, showing that this approach has considerable promise for characterizing complex colloidal materials.