Determination of Total Iron in Environmental Samples by Solid Phase Extraction with Dimethyl(E)-2-(2-methoxyphenoxy)-2-butenedioate Gholamreza Khayatian,* Hamidreza Ahmadzadeh Vosta Kolaie, Farough Nasiri, Bahareh Atashkar and Shahed Hassanpoor Department of Chemistry, Faculty of Science, University of Kurdistan, Sanandaj, Iran A novel solid phase extraction technique for determination of total iron in environmental water sam- ples was developed. The method is based on sorption of Fe(III) ions on octadecyl silica membrane disk modified with a new synthetic ligand dimethyl(E)-2-(2-methoxyphenoxy)-2-butenedioate (I). Iron(III) is quantitatively retained on the disk in the pH range of 3-7 at a flow rate of 1-7 mL min -1 . The Fe(III) eluted with 10 mL of 0.01 M EDTA and than was measured by flame atomic absorption spectrometry (FAAS) at 248.3 nm. The maximum capacity disk modified by 7 mg of ligand was found to be 197 ± 2 mg of iron(III). The breakthrough volume was greater than 2000 mL. The iron(III) was completely recovered (> 99%) from water with a preconcentration factor of more than 200. The limit of detection of the proposed method was 1.00 ng mL -1 . The various cationic and anionic interferences had no effect on the recovery of iron(III) from the binary mixtures. The proposed method was successfully applied to determination of total iron from three different water samples. Keywords: Solid phase extraction; Total iron determination; Iron(III) preconcentration. 1. INTRODUCTION Iron is widely distributed in nature and is one of the most important elements in environmental and biological systems as many kinds of compounds. 1-3 The U.S. Environ- mental Protection Agency have established a contaminant level in drinking water at 0.3 mg l -1 for iron. 4 Numerous techniques, such as spectrophotometric. 3,5,6 potentiometric titration 7 flame 8 and electrothermal atomic absorption spectrophotometry, 9 flow-injection 10-14 and photoacous- tic 15 methods, have been used for the determination of iron species. However, due to the low levels of iron in environ- mental samples, its separation from other coexisting ele- ments is essential, and usually necessitates a preconcentra- tion step prior to iron determination. Traditional preconcentration and separation methods for metal ions are liquid-liquid extraction, coprecipitation, and ion-exchange, etc. These methods often require large amount of high purity organic solvent, some of which are harmful to health and cause environmental problems. 16 Nowadays, the solid-phase extraction (SPE) is being widely utilized for preconcentration or separation of metals due to following advantages. These include, higher enrichment factors, absence of emulsion, safely with respect to hazard- ous samples, minimal costs due to low consumption of re- agents, flexibility and easy of automation. 17-21 Recently, SPE were successfully utilized for the extraction and analy- sis of iron ions. 1,3,21-42 In this paper, we report using of recently synthesized ligand, namely, dimethyl(E)-2-(2-methoxyphenoxy)-2-bu- tenedioate (I) (DMPB, Fig. 1) 43 as a new reagent for solid- phase extraction of iron(III) ion, which exhibit high selec- tivity for iron(III) ion over metal cations. 2. EXPERIMENTAL 2.1. Apparatus The determination of iron(III) and other cations were performed on a Shimadzu AA-670 atomic absorption spectrophotometer (Kyoto, Japan) under the recommended 118 Journal of the Chinese Chemical Society, 2010, 57, 118-123 * Corresponding author. E-mail: gkhayatian@yahoo.com Fig. 1. Structure of ligand (I).