While dextrans have cation binding properties, their chemical modification to carboxymethyl and hydroxamate dextrans increase the degree of metal ion chelation. This paper describes recent findings on the use of dextran coated silica materials for the on-line preconcentration of metal ions in ion chromatography. Results presented include the effects of flow-rate and pH on metal ion uptake and elution, metal ion complexation capacities and applications to trace metal analysis in aqueous environmental samples.