SYNTHESIS AND CHROMATOGRAPHIC CHARACTERIZATION OF DEXTRAN-COATED ZIRCONIA HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC STATIONARY PHASES

Porous zirconia particles made by the oil emulsion (OE) method and the polymerization-induced colloid aggregation (PICA) method have been co ated with a small, carboxymethylated (similar to 5%) dextran polymer a nd crosslinked in place. The parameters of the coating process (dextra n concentration, adsorption time and crosslinker concentration) have a ll been examined and an optimum value for each determined. The coated and uncoated materials were characterized by nitrogen sorptometry and size-exclusion chromatography (SEC) using solutes (polystyrenes and de xtrans) of well-defined molecular masses. Nitrogen sorptometry results show that the PICA material has a much lower pore volume and smaller pore diameter than do the OE materials. Despite this, the elution volu mes of the SEC probes change very little upon polymer coating the PICA material while the OE material shows a very large change upon coating .