A double template imprinted sorbent with chelating diamines was prepared by sol-gel process for the selective separation and enrichment of trace Fe(III) from natural water samples prior to its determination by flame atomic adsorption spectroscopy (FAAS). The resulting materials were characterized by SEM, FTIR, elemental analysis and nitrogen gas adsorption-desorption. Compared with the CTAB imprinted sorbent (CTAB-imp) and the Fe(III) imprinted sorbent (Fe-imp), the double template imprinted sorbent (Fe-CTAB-imp) had higher selectivity and adsorption capacity for Fe(III). In the presence of Cr(III) ion, selectivity coefficient of the Fe-CTAB-imp for Fe(III) were 261 and 267, respectively, which are much higher than that of CTAB-imp (1.61 and 1.32). The uptake capacities of the Fe-CTAB-imp were much higher than those of sorbents prepared without CTAB template. The relative selectivity coefficient of the Fe-CTAB-imp for Fe(III)/Cr(III) was 68.9 times greater than the Fe-imp. The sorption isotherms on the Fe-CTAB-imp conformed to the Langmuir equation, and the theoretical sorption capacity was 36.90 +/- 3.16 mg/g. Furthermore, the Fe-CTAB-imp possessed fast sorption kinetics for Fe(III) from aqueous solution with a saturation time of less than 5 min, and could be used repeatedly. Combined with FAAS, the method detection limit for Fe(III) could reach the level of 0.26 ng/mL. This sorbent has been successfully applied to the separation and determination of trace Fe(III) in reference materials, artificial seawater, fresh water and nearshore seawater samples with satisfactory results. (C) 2012 Elsevier B.V. All rights reserved.