Speciation of arsenite and arsenate by electrothermal AAS following ionic liquid dispersive liquid-liquid microextraction
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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 1-butyl-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 μg L−1 As(III) are 13 ng L−1 and 4.9 %, respectively. The method was successfully applied to the determination 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
The authors would like to thank the German Research Foundation for base funding within the Emmy Noether program to Britta Planer-Friedrich (Grant PL 302/3-1). We would also like to thank Prof. Dr. Stefan Peiffer at University of Bayreuth for providing access to the instrumental (ETAAS) facility. Dr. Markus Bauer and Martina Rohr are gratefully acknowledged for their valuable suggestions on ETAAS analysis and Uwe Kunkel for providing river water samples.
- 2.Hernandez-Zavala A, Valenzuela OL, Matousek T, Drobna Z, Dedina J, Garcia-Vargas GG, Thomas DJ, Del Razo LM, Styblo M (2008) Speciation of arsenic in exfoliated urinary bladder epithelial cells from individuals exposed to arsenic in drinking water. Environ Health Perspect 116:1656–1660CrossRefGoogle Scholar
- 6.Arsenic in Drinking Water, http://water.epa.gov/lawsregs/rulesregs/sdwa/arsenic/index.cfm
- 7.Guidelines for Drinking-water Quality, First addendum to third edition, Volume 1: http://www.who.int/water_sanitation_health/dwq/gdwq0506.pdf
- 8.Mushak P (2000) Arsenic and old laws, a scientific and public health analysis of arsenic occurrence in drinking water, its health effects, and EPA’s outdated arsenic water standard. http://www.nrdc.org/water/drinking/arsenic/chap1.asp
- 13.Shemirani F, Baghdadi M, Ramezani M (2005) Preconcentration and determination of ultra trace amounts of arsenic(III) and arsenic(V) in tap water and total arsenic in biological samples by cloud point extraction and electrothermal atomic absorption spectrometry. Talanta 65:882–887CrossRefGoogle Scholar
- 24.Yousefi SR, Ahmadi SJ (2011) Development a robust ionic liquid-based dispersive liquid-liquid microextraction against high concentration of salt combined with flame atomic absorption spectrometry using microsample introduction system for preconcentration and determination of cobalt in water and saline samples. Microchim Acta 172:75–82CrossRefGoogle Scholar
- 30.Zhang Q, Minami H, Inoue S, Atsuya I (2004) Differential determination of trace amounts of arsenic(III) and arsenic(V) in seawater by solid sampling atomic absorption spectrometry after preconcentration by coprecipitation with a nickel–pyrrolidine dithiocarbamate complex. Anal Chim Acta 508:99–105CrossRefGoogle Scholar
- 33.Heinrichs G (1996) Arsenkonzentrationen in Grundwässern. In: Forschungsergebnisse aus dem Bereich Hydrogeologie und Umwelt, Heft 12, Lehr- und Forschungsbereich Hydrogeologie und Umwelt der Universität Würzburg (Hsrg.)Google Scholar