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Title: Speciation of arsenic(III)/arsenic(V) and selenium(IV)/ selenium(VI) using coupled ion chromatography - hydride generation atomic absorption spectrometry

Author
item Goldberg, Sabine
item MANNING, BRUCE - San Francisco State University

Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 5/16/2012
Publication Date: 2/20/2014
Citation: Goldberg, S.R., Manning, B.A. 2014. Speciation of arsenic(III)/arsenic(V) and selenium(IV)/ selenium(VI) using coupled ion chromatography - hydride generation atomic absorption spectrometry. In: DeLaune, R., et al., editors. Methods in biogeochemistry of wetlands. Madison, WI:Soil Science Society of America. p. 801-814.

Interpretive Summary: Arsenic and selenium are essential trace elements that can be toxic to animals at elevated concentrations. Arsenic occurs in two oxidation states, arsenic(III) and arsenic(V) and selenium occurs in two oxidation states, selenium(IV) and selenium(VI). The arsenic(III) and selenium(IV) oxidation states are considered to be more toxic than the arsenic(V) and selenium(VI) states. For this reason, analytical methods must differentiate between the two elemental states. A rapid continuous flow-through method has been developed to quantify arsenic and selenium according to oxidation state at the part per billion level of concentration. Since arsenic and selenium may be present in elevated amounts in soil solution and drainage waters, the accurate analysis of these elements is important. This method can be used by researchers and action and regulatory agencies to identify waters high in arsenic and/or selenium, as well as to identify the dominant arsenic and/or selenium oxidation state.

Technical Abstract: Simple analytical methods have been developed to speciate inorganic arsenic and selenium in the ppb range using coupled ion chromatography-hydride generation atomic absorption spectrometry. Because of the differences in toxicity and adsorption behavior, determinations of the redox states arsenite As(III) and arsenate As(V) and selenite Se(IV) and selenate Se(VI) are important. We used anion exchange chromatography to separate As(III) and As(V) or Se(IV) and Se(VI) based on differences in retention times. Samples were then mixed with concentrated HCl for As or Se determination as the hydrides. Detection limits were 0.8 ppb As for both redox states and 0.68 ppb for Se(IV) and 0.55 ppb for Se(VI). Spiking of actual mixed sample solutions of both redox states showed the procedure to be accurate for solutions with As(III)/As(V) or Se(IV)/Se(VI) ratios ranging from 1:4 to 4:1. Average recoveries were 95.7% for As (III), 106% for As(V), 93.1% for Se(IV), and 108% for Se(VI). The technique was used to determine As(III) and As(V) and Se(IV) and Se(VI) in deionized water and actual and synthetic irrigation waters.