Journal of Hazardous Materials 164 (2009) 133–137 Contents lists available at ScienceDirect Journal of Hazardous Materials journal homepage: www.elsevier.com/locate/jhazmat Enrichment of trace amounts of copper(II) ions in water samples using octadecyl silica disks modified by a Schiff base ionophore prior to flame atomic absorption spectrometric determination S.A.M. Fathi, M.R. Yaftian ∗ Department of Chemistry, Faculty of Science, Zanjan University, PO Box 45195-313 Zanjan, Iran article info Article history: Received 14 December 2007 Received in revised form 9 July 2008 Accepted 31 July 2008 Available online 6 August 2008 Keywords: Copper(II) Solid phase extraction Preconcentration Schiff base abstract Bis(5-bromo-2-hydroxybenzaldehyde)-1,2-propanediimine is synthesized by the reaction of 5-bromo-2- hydroxybenzaldehyde and 1,2-diaminopropane in ethanol. This ligand is used as a modifier of octadecyl silica disks for preconcentration of trace amounts of copper(II) ions, followed by nitric acid elution and flame atomic absorption spectrometric (FAAS) determination. The effect of parameters influencing the extraction efficiency, i.e. pH of the sample solutions, amount of the Schiff base, type and volume of strip- ping reagent, sample and eluent flow rates were evaluated. Under optimum experimental conditions, the capacity of the membrane disks modified by 4 mg of the ligand was found to be 247.7 (±2.1) g of copper. The detection limit and the concentration factor of the presented method are 2.4ng/l and greater than 400, respectively. The method was applied to the extraction, recovery and detection of copper in different synthetic and water samples. © 2008 Elsevier B.V. All rights reserved. 1. Introduction Copper is known as an important element in industry and bio- logical systems as well. It is an essential nutrient to all high plants and animals. Copper is found in the bloodstream of animals, as a co-factor in various enzymes. This element can be also poisonous and even fatal to organisms. A concentration more than 1 g/ml can impart a bitter taste to water. Large oral doses can cause vomit- ing and may eventually cause liver damage. Copper concentration in potable water is usually very low (≤20 g/l) [1]. The concentra- tion of copper in lakes and rivers ranges from 0.5 to 1000 g/l with an average concentration of 10 g/l. In groundwater the average of copper concentration (5 g/l) is similar to that in lakes and rivers. Some groundwater contains up to 2800 g/l, that is above the stan- dard level for drinking water [2]. Copper can inhibit the activity of dihydrophil hydratase, an enzyme involved in haemopoiesis. Symp- toms of copper poisoning are very similar to those produced by arsenic. Fatal cases are generally terminated by convulsions, palsy, and insensibility. Therefore, a precise, accurate and rapid measure- ment of copper is much interest. Flame and graphite furnace atomic absorption spectrometry [3] and spectrophotometric methods [4] are known as the most ∗ Corresponding author. Tel.: +98 241 5152581; fax: +98 241 2283203. E-mail address: yaftian@znu.ac.ir (M.R. Yaftian). common methods for determination of copper in various samples. However, these methods suffer from their insufficient sensitivity for very low concentration of the metal in environmental and bio- logical samples. To overcome such problems, an enrichment and matrix elimination step is sometimes required before applying the above-mentioned techniques. Various separation and precon- centration methods have been proposed to achieve these goals. Among them are solvent extraction [5], cloud point extraction [6], membrane filtration [7], ion exchange [8] and coprecipitation [9] techniques. Solid phase extraction (SPE) is an alternative technique for liquid–liquid extraction for preconcentration purposes. It reduces the disposal costs, extraction time, and consumption of hazardous organic solvents [10,11]. Octadecyl-bonded silica disks modified by suitable ionophores have been successfully applied for solid phase extraction, separation, preconcentration and determination of different metal ions [12]. Undoubtedly, modifiers (ligands) play a crucial role in the success of such method. Owing to their coordinating ability with a variety of metal ions, Schiff base ligands have been involved in various analytical investigations for many years. They are a category of important sensory molecules for fabricating cation- [13] and anion- [14] selec- tive electrodes. Shemirani et al. [15] have studied the application of bis(2-methoxybenzaldehyde)ethylenediimine as a complexing agent for Cr(III) ions and a subsequent entrapment of this complex in surfactant micelles for enrichment and separation of chromium ions. In addition, various Schiff base ligands of type N 2 O 2 were used 0304-3894/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.jhazmat.2008.07.138