Abstract Poly- l-aspartic acid (PLAsp), a biopolymer, and a similar synthetic polymer, poly-acrylic acid (PAA), each consisting of ∼50 repeating Asp and acrylic acid monomers, respectively, were immobilized onto controlled pore glass (CPG) and evaluated for use as metal ion-exchange materials. Both polymers achieve metal complexation primarily through their repeating carboxylate side groups resulting in a similar binding trend for the metals tested (Ca 2+, Cd 2+, Co 2+, Cu 2+, Mg 2+, Mn 2+, Na +, Ni 2+, Pb 2+), with metal binding capacities ranging from <0.1 to 12 μmol metal/g column and <0.1 to 32 μmol metal/g column for PLAsp and PAA respectively. Cu 2+ and Pb 2+ exhibited strong binding to both materials, while the other metals demonstrated only weak or minimal binding. Both columns allowed for quantitative release of bound metals through acid stripping and experienced increased overall metal binding with increasing pH. Both systems also maintained similar structural and chemical stability when continuously exposed to neutral buffered, highly acidic, oxidizing, large molecule rich, and elevated temperature environments. The main differences between the two systems are the material cost and system biodegradability.