Flame atomic absorption spectrometric determination of Cd, Pb, and Cu in food samples after pre-concentration using 4-(2-thiazolylazo) resorcinol-modified activated carbon Mohamed Habila a , Erkan Yilmaz b , Zeid A. ALOthman a , Mustafa Soylak b, * a Chemistry Department, College of Science, King Saud University, Riyadh 11451, Saudi Arabia b Erciyes University, Science Faculty, Department of Chemistry, Kayseri 38039, Turkey 1. Introduction Heavy metal contamination is considered one of the most important environmental problems because of the accumulation of these metals in plants, animals and, finally, humans. Heavy metals enter the environment due to their widespread use in fertilizers, plastic products, and pigments [1–4]. Therefore, scientists are focusing on analyzing heavy metals in environmental samples, which may have concentrations of heavy metals in the mg/g, ng/g, and pg/g ranges. [5–9]. Many methods have been used for heavy metal analysis, such as flame atomic absorption spectrometry (FAAS) [10], inductively coupled plasma atomic emission spectrometry (ICP-AES) [11], and inductively coupled plasma mass spectrometry (ICP-MS) [12]. There is continuing interest in the development of new analytical techniques with greater efficiency and the ability to achieve fast and accurate results [13]. However, the detection limits of analytical instru- ments are currently still higher than the lowest permitted limits for environmental pollutants; therefore, sensitive and precise sample pretreatment procedures must be developed to allow the determination of the concentrations of pollutants that are present at low concentrations in environmental samples [14]. Extraction is an important step in the analysis of environmental samples, especially when the analyzed pollutant is not homo- geneously distributed in the sample or its physical or chemical form is not suitable for direct detection. In addition, in some cases, the targeted analytes in real samples are surrounded by the sample matrix [15,16]. Solid-phase extraction (SPE) is an effective, fast, and simple pretreatment procedure to achieve pollutant/matrix separation and preconcentration [17–20]. SPE is based on the efficient adsorption of pollutants from the whole real sample matrix followed by recovery using a suitable eluent to achieve a high preconcentration factor. The primary aim of SPE is to separate and preconcentrate the pollutant so that it is in the detection range of the available instruments [21–23]. Commercial activated carbon is widely used for preconcentra- tion and the determination of heavy metal concentrations [24–26]. However, the use of commercial activated carbon is limited due to the high costs [27]. These high costs have led to the search for other suitable alternatives that are more economical but still effective for SPE [28–30]. The search for economical and high-efficiency adsorbents is an important area of scientific research. In the present a low-cost activated carbon prepared from wastes of Riyadh city, Kingdom of Saudi Arabia (KSA) and modified with 4-(2-thiazolylazo) resorcinol. It was firstly and successfully used as a solid-phase extractor for traces levels of Cd(II), Pb(II), and Cu(II). Factors controlling the efficiency of SPE, including the pH, eluent type, eluent volume, test solution flow rate, eluent flow rate, sample volume, and matrix, were optimized. The proposed method Journal of Industrial and Engineering Chemistry xxx (2014) xxx–xxx A R T I C L E I N F O Article history: Received 25 August 2013 Accepted 29 December 2013 Available online xxx Keywords: Solid-phase extraction Activated carbon Heavy metals Flame atomic absorption spectrometry A B S T R A C T This work aimed to develop a solid-phase extraction method using low-cost activated carbon produced from waste and modified with 4-(2-thiazolylazo) resorcinol for Cd(II), Pb(II), and Cu(II). The results showed that quantitative recovery of analytes was obtained at pH 6 with 3 M nitric acid as the eluent and a sample volume up to 1000 mL. The method was validated using certified reference material and addition-recovery tests. The limits of detection (LODs) for Pb(II), Cd(II), and Cu(II) were 2.03 mg L À1 , 0.15 mg L À1 , and 0.19 mg L À1 , respectively. The procedure was applied for determination of analytes in food samples. ß 2014 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved. * Corresponding author. Tel.: +903522076666/33150; fax: +903524374933. E-mail address: soylak@erciyes.edu.tr (M. Soylak). G Model JIEC-1831; No. of Pages 5 Please cite this article in press as: M. Habila, et al., J. Ind. Eng. Chem. (2014), http://dx.doi.org/10.1016/j.jiec.2013.12.101 Contents lists available at ScienceDirect Journal of Industrial and Engineering Chemistry jou r n al h o mep ag e: w ww .elsevier .co m /loc ate/jiec 1226-086X/$ – see front matter ß 2014 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.jiec.2013.12.101