The water-soluble poly(N-maleyl glycine-co-acrylamide) (P(MG-co-Am)) reagent with strong complexing properties for the inorganic ions Cr(III), Co(II), Zn(II), Ni(II), Cu(II), Cd(II), Pb(II), Hg(II), As(V), and Se(IV) was investigated in aqueous phase in conjunction with membrane filtration using the Liquid-phase Polymer-based Retention (LPR) technique. The P(MG-co-Am) was shown to be useful for retention of different inorganic ions and their separation from elements not bound to the polymeric reagent. The inorganic ion interaction with the hydrophilic polymer was determined as a function of pH and filtration factor. At higher pH, the copolymer can be applied to the separation and preconcentration of most of the inorganic ions. Viscosimetric measurements of the copolymers were performed in the presence of metal ions at different pH values.