The synthesis and characterization of poly(ethylenediaminetetraacetic acid-co-lactose) with pendant carboxylic groups of high molar mass (132 kg mol(-1)) is described. The polycondensate was hydrolytically and microbiologically degradable with conventional microbiological methods. The metal-complexing properties of the polyester were studied for Cr(III), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Sr(II), Cd(II), Pb(II), and AI(III) ions in aqueous solution with the liquid-phase polymer-based retention (LPR) method. In addition, the complexing capacity of the Cu(II)-saturated copolymer was determined by thermogravimetric analysis to be 182 mg g(-1) of polymer. According to the retention profiles determined as a function of the filtration factor with LPR in conjunction with inductively coupled plasma spectrometry, Cr(III) and Fe(III) showed a strong interaction with this polymer under these conditions, as indicated by retention values of about 100% at pH 5. (C) 2003 Wiley Periodicals, Inc.