Submitted to: Soil Science Society of America Journal
Publication Type: Peer reviewed journal
Publication Acceptance Date: 7/26/2005
Publication Date: 1/1/2006
Citation: Goldberg, S.R., Martens, D.A., Forster, H.S., Herbel, M.J. 2006. Speciation of selenium(iv) and selenium(vi) using coupled ion chomatography - hydride generation atomic absorption spectrometry. Soil Science Society of America Journal. 70(1):41-47. Interpretive Summary: Selenium is an essential trace element that can be toxic to animals at elevated concentrations. It occurs in two oxidation states, selenium(IV) and selenium(VI). The selenium(IV) oxidation state is considered to be more toxic than the selenium(VI) state. For this reason, analytical methods must differentiate between the two states. A rapid continuous flow-through method has been developed to quantitate selenium according to oxidation state at the part per billion level of concentration. Since selenium may be present in elevated amounts in soil solution and drainage waters, its accurate analysis is important. This method can be used by researchers, action and regulatory agencies to identify waters high in selenium, as well as to identify the dominant selenium oxidation state.
Technical Abstract: A simple method was developed to speciate inorganic selenium in the microg/L range using coupled ion chromatography-hydride generation atomic absorption spectrometry. Because of the differences in toxicity and adsorption behavior determination of the redox states selenite, Se(IV), and selenate, Se(VI), is important. We used anion exchange chromatography to separate Se(IV) and Se(VI) based on differences in retention times. Samples were then mixed with concentrated HCl and passed through 130 centigrade sand bath to reduce Se(VI) to Se(IV) for Se determination as the hydride. Detection limits were 0.68 microg/L for Se(IV) and 0.55 microg/L for Se(VI). Spiking of actual sample solutions with Se(IV) and Se(VI) showed the procedure to be accurate for solutions with Se(IV)/Se(VI) ratios ranging from 1:4 to 4:1. Average recovery was 93.1% for Se(IV) and 108% for Se(VI). The technique was used to determine Se(IV) and Se(VI) in deionized water and actual and synthetic irrigation waters.