Analytical Sciences

Speciation of Chromium in Seawater by ICP-AES with Dual Mini-columns Containing Chelating Resin

Takashi SUMIDA,* Akhmad SABARUDIN,** Mitsuko OSHIMA,** and Shoji MOTOMIZU**

*Kochi Prefectual Industrial Technology Center, Nunoshida 3992-3, Kochi 781-5101, Japan
**Department of Chemistry, Faculty of Science, Okayama University, Tsushimanaka 3-1-1, Okayama 700-8530, Japan

A method for the preconcentration and speciation of chromium in seawater was developed. On-line preconcentration and determination were carried out by using inductively coupled plasma atomic emission spectrometry (ICP-AES) with dual mini-columns containing a chelating resin. In this system, Cr(III) was collected on the first column. The effluent containing residual chromium from the first column was collected on the second column after passing through a reduction-switching unit, in which the reducing agent was introduced, or not, for the reduction of Cr(VI) to Cr(III). Cr(VI) was determined as the difference between the concentration of pre-reduced Cr(VI) and Cr(III) in the effluent from the first column. The detection limits for Cr(III) and Cr(VI) were 0.04 and 0.09 µg l^-1, respectively.

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