Analytical Sciences

Simultaneous Determinations of Cr(VI) and Cr(III) by Ion-Exclusion/Cation-Exchange Chromatography with an Unmodified Silica-Gel Column

Shizuko HIRATA,* Daisuke KOZAKI,* Kinya SAKANISHI,** Nobukazu NAKAGOSHI,* and Kazuhiko TANAKA*

*Graduate School for International Development and Cooperation, Hiroshima University, 1-5-1 Kagamiyama, Higashi-hiroshima 739-8529, Japan
**Biomass Technology Center, National Institute of Advanced Industrial Science and Technology, 2-2-2 Hiro-suehiro, Kure 739-0197, Japan

In order to characterize the ion-exclusion and cation-exchange properties of an unmodified silica-gel column, the retention behaviors of Cr(VI) and Cr(III) ions were investigated using a Develosil 30-5 (150 × 4.6 mm i.d.) in the acidic region. Cr(VI) was separated from other anions by an ion-exclusion and ion-adsorption mechanism, and Cr(III) was separated from other cations with a cation-exchange mechanism. When using 2.0 mM oxalic acid (pH 2.6) as an eluent, a good separation of Cr(VI) and Cr(III) was obtained using conductimetric detection in 12 min. The method was successfully applied to the simultaneous determinations of Cr(VI) and Cr(III) added into tap-water and river-water samples.

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