The macromonomer polyethylene glycol methylether methacrylate was homo- and copolymerized with 2-acrylamido-2-methyl-1-propane sulfonic acid under three feed monomer ratios. The initiator used was ammonium peroxydisulfate (0.2 mol %). All the polymers were completely soluble in water. The copolymer composition was determined by elemental analysis. The metal ion interaction capability of the three polymers was investigated through the liquid-phase polymer-based retention (LPR) technique at different values of pH and filtration factor Z. The highest metal ion retention ability was observed at pH 5.0. The homopolymer showed a high selectivity for Ni(II) ions at pH 3.0. The copolymers (PEGMEM)(1.51)-co-(APSA)(1.00) and (PEGMEM)(1.00)-co-(APSA)(1.95) showed a high selectivity for Cr(III) ions at pH 3.0. The maximum retention capacity, in general, was similar for the homo- and copolymers. (C) 2004 Wiley Periodicals, Inc.