Wednesday, November 15, 2006 - 9:45 AM
279-3

Speciation of selenium(IV) and selenium(VI) using coupled ion chromatography-hydride generation atomic absorption spectrometry.

Sabine Goldberg1, Dean A. Martens2, Harold S. Forster1, and Mitchell Herbel3. (1) USDA-ARS, Salinity Laboratory, 450 W. Big Springs Rd., Riverside, CA 92507, (2) USDA-ARS Southwest Watershed Research Center, 2000 E. Allen Rd., Tucson, AZ 85719, (3) U.S. Salinity Lab, 2222 Curtis Avenue Unit B, Redondo Beach, CA 90278

A simple method was developed to speciate inorganic selenium in the µg L-1 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 a 130 oC sand bath to reduce Se(VI) to Se(IV) for Se determination as the hydride.  Detection limits were 0.68 µg L-1 for Se(IV) and 0.55 µg L-1 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.

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