Research Article Separation/Preconcentration and Speciation Analysis of Trace Amounts of Arsenate and Arsenite in Water Samples Using Modified Magnetite Nanoparticles and Molybdenum Blue Method Mohammad Ali Karimi, 1,2 Alireza Mohadesi, 1,3 Abdolhamid Hatefi-Mehrjardi, 1,2 Sayed Zia Mohammadi, 1,3 Javad Yarahmadi, 2 and Azadeh Khayrkhah 2 1 Department of Chemistry, Payame Noor University, P.O. Box 19395-4697, Tehran, Iran 2 Department of Chemistry & Nanoscience and Nanotechnology Research Laboratory (NNRL), Payame Noor University, Sirjan, P.O. Box 78185-347, Iran 3 Department of Chemistry, Payame Noor University, Kerman, Iran Correspondence should be addressed to Mohammad Ali Karimi; ma karimi43@yahoo.com Received 4 May 2013; Revised 16 November 2013; Accepted 17 November 2013; Published 2 March 2014 Academic Editor: Daryoush Afzali Copyright © 2014 Mohammad Ali Karimi et al. his is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. A new, simple, and fast method for the separation/preconcentration and speciation analysis of arsenate and arsenite ions using cetyltrimethyl ammonium bromide immobilized on alumina-coated magnetite nanoparticles (CTAB@ACMNPs) followed by molybdenum blue method is proposed. he method is based on the adsorption of arsenate on CTAB@ACMNPs. Total arsenic in diferent samples was determined as As(V) ater oxidation of As(III) to As(V) using potassium permanganate. he arsenic concentration has been determined by UV-Visible spectrometric technique based on molybdenum blue method and amount of As(III) was calculated by subtracting the concentration of As(V) from total arsenic concentration. MNPs and ACMNPs were characterized by VSM, XRD, SEM, and FT-IR spectroscopy. Under the optimal experimental conditions, the preconcentration factor, detection limit, linear range, and relative standard deviation (RSD) of arsenate were 175 (for 350 mL of sample solution), 0.028 g mL −1 , 0.090–4.0 g mL −1 , and 2.8% (for 2.0 g mL −1 , =7), respectively. his method avoided the time-consuming column-passing process of loading large volume samples in traditional SPE through the rapid isolation of CTAB@ACMNPs with an adscititious magnet. he proposed method was successfully applied to the determination and speciation of arsenic in diferent water samples and suitable recoveries were obtained. 1. Introduction Speciation analysis refers to the process of identiication and determination of diferent physical and/or chemical species in a sample. Arsenic contamination in environmen- tal waters supply is a worldwide problem and despite the analytical advances made in the ield of speciation analysis of this element during the last decades, there are still a relatively limited number of studies dealing with the deter- mination of arsenate and arsenite species in real samples such as natural waters [1]. he toxicity of arsenic highly depends on its inorganic and organic chemical forms. In natural waters, arsenic is predominantly present in inor- ganic forms of As(III) and As(V) [2]. As(III) is several hundred times more toxic than organoarsenic and 25–60 times more toxic than As(V) [3]. hus, it is important to determine each of arsenic species rather than the total amount of arsenic in water samples. Except for some like electroanalytical methods [4], simultaneous and direct deter- mination of As(III) and As(V) species is diicult by other instrumental techniques such as UV-Visible. molecular absorption spectrometry. In recent years, several methods of simultaneous separation/preconcentration and speciation of As(III) and As(V), such as hydride generation [5, 6], Hindawi Publishing Corporation Journal of Chemistry Volume 2014, Article ID 248065, 9 pages http://dx.doi.org/10.1155/2014/248065