Separation/preconcentration and speciation analysis of trace amounts of arsenate and arsenite in water samples using modified magnetite nanoparticles and molybdenum blue method

Abstract

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. The method is based on the adsorption of arsenate on CTAB@ACMNPs. Total arsenic in different samples was determined as As(V) after oxidation of As(III) to As(V) using potassium permanganate. The 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, n = 7), respectively. This 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. The proposed method was successfully applied to the determination and speciation of arsenic in different water samples and suitable recoveries were obtained. © 2014 Mohammad Ali Karimi et al.