Abstract: Water-insoluble polymer resins containing ethylenediamine subunits which are N-substituted with a functional group chosen from the group consisting of --H, --CS.sub.2, --CH.sub.2 PO.sub.3 H, and --CH.sub.3, or which are N-quarternized as --[N(CH.sub.3).sub.2.sup..sym..crclbar. OH]--, and polysalts of these. The use of such resins in separating nitrites, organic chlorine compounds, (heavy) metal ions including radioactive metal ions, counteranions of metal ions, and aliphatic and aromatic aldehydes from dilute aqueous solutions, especially at low concentrations. A method of synthesizing epoxy carbamate resins without violent reaction by inverse suspension condensation in cold liquid paraffin or toluene, preferably with dimethyl formamide or 1-methyl-2-pyrrolidone as co-solvents.