By the method of solid phase spectroscopy studied chemical-analytical properties of the sorbent based on a copolymer of maleic anhydride with styrene, modified with p-amino benzoic acid and the polymer-chelate complex with iron(III) ions. Found the time to reach equilibrium sorption process, the dependence of the degree of extraction of metal from the solid phase acidity and sorption capacity. Investigation sorption of iron(III) on the synthesized sorbent. The prospects of analytical use of solid phase for concentration and separation of iron(III) solutions of complex composition. Developed an effective method for determination of iron(III) in tap water.