Speciation of arsenite and arsenate by electrothermal AAS following ionic liquid dispersive liquid-liquid microextractio
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ORIGINAL PAPER
Speciation of arsenite and arsenate by electrothermal AAS following ionic liquid dispersive liquid-liquid microextraction Sasan Rabieh & Mozhgan Bagheri & Britta Planer-Friedrich
Received: 23 September 2012 / Accepted: 18 January 2013 / Published online: 30 January 2013 # Springer-Verlag Wien 2013
Abstract We have developed a new method for the microextraction and speciation of arsenite and arsenate species. It is based on ionic liquid dispersive liquid liquid microextraction and electrothermal atomic absorption spectrometry. Arsenite is chelated with ammonium pyrrolidinedithiocarbamate at pH 2 and then extracted into the fine droplets of 1butyl-3-methylimidazolium bis(trifluormethylsulfonyl) imide which acts as the extractant. As(V) remains in the aqueous phase and is then reduced to As(III). The concentration of As(V) can be calculated as the difference between total inorganic As and As(III). The pH values, chelating reagent concentration, types and volumes of extraction and dispersive solvent, and centrifugation time were optimized. At an enrichment factor of 255, the limit of detection and the relative standard deviation for six replicate determinations of 1.0 μgL−1 As(III) are 13 ngL−1 and 4.9 %, respectively. The method was successfully applied to the determination
Electronic supplementary material The online version of this article (doi:10.1007/s00604-013-0946-2) contains supplementary material, which is available to authorized users. S. Rabieh (*) Faculty of Chemistry, Shahid Beheshti University, 1983963113 Tehran, Iran e-mail: [email protected] S. Rabieh Environmental Geochemistry, Faculty of Biology, Chemistry and Earth Sciences, University of Bayreuth, Universitaetsstrasse 30, 95447 Bayreuth, Germany e-mail: [email protected] M. Bagheri Advanced Materials and Nanotechnology Department, Materials and Energy Research Center, Karaj, Iran B. Planer-Friedrich Environmental Geochemistry, Faculty of Biology, Chemistry and Earth Sciences, University of Bayreuth, Universitaetsstrasse 30, 95447 Bayreuth, Germany
of As(III) and As(V) in spiked samples of natural water, with relative recoveries in the range of 93.3–102.1 % and 94.5–101.1 %, respectively. Keywords [BMIM][NTf2] . Arsenic . Dispersive liquid liquid microextraction . ETAAS
Introduction Inorganic arsenic is a known human carcinogen that can induce skin, bladder, and liver tumours and the element ranks first on the list of hazardous substances established by the Agency for Toxic Substances and Disease Registry of the US Environmental Protection Agency (EPA) [1–4]. Total arsenic concentrations in natural waters range from less than 1 μgL−1 to more than 5 mgL−1, with arsenite and arsenate generally being the most predominant species [5]. The current drinking standard set by the EPA and the World Health Organization is 10 μgL−1 [6, 7]. However, even at 10 μgL−1 the risk of arsenic-induced cancer is still 1 in 500 [8]. Compared to the EPA’s general risk management guideline for permissible skin cancer risk (1 in 10,000) and the guide
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