Analytical Sciences

Determination of Iodide, Iodate and Total Iodine in Natural Water Samples by HPLC with Amperometric and Spectrophotometric Detection, and Off-line UV Irradiation

Akira TAKEDA,* Hirofumi TSUKADA,* Yuichi TAKAKU,* Naoya SATTA,** Mitsuhisa BABA,*** Toshihiro SHIBATA,* Hidenao HASEGAWA,* Yusuke UNNO,* and Shun’ichi HISAMATSU*

*Department of Radioecology, Institute for Environmental Sciences, 1-7 Ienomae, Obuchi, Rokkasho, Kamikita, Aomori 039-3212, Japan
**Faculty of Agriculture, Iwate University, 3-18-8 Ueda, Morioka, Iwate 020-8550, Japan
***School of Veterinary Medicine, Kitasato University, 23-35-1 Higashi, Towada, Aomori 034-8628, Japan

We developed a rapid, simple method for the iodine speciation analysis of water and applied it to natural water samples. Simultaneous determinations of I⁻ and IO₃⁻ were achieved with an HPLC system with amperometric detection for I⁻ and spectrophotometric detection after a postcolumn reaction for IO₃⁻. We determined the I⁻ and IO₃⁻ concentrations in 20-μL water samples within 10 min. Total I concentrations in water samples were determined after the decomposition of organics by off-line UV irradiation for 30 min, followed by reduction to I⁻. The analytical conditions were optimized by using test solutions rich in organic matter extracted from soils. We tested the new method with samples of groundwater, spring water, precipitation, soil percolate, stream water, and seawater as well as solutions extracted from soil. The method worked well, although the concentrations of some I species were below detection. This method is suitable for routine speciation analysis, which is important for studies of I behavior in the environment.

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