Simultaneous determinations of Cr(VI) and Cr(III) by ion-exclusion/cation-exchange chromatography with an unmodified silica-gel column

Abstract

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 × 4.6mm 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 2.0mM oxalic acid (pH 2.6) as an eluent, a good separation of Cr(VI) and Cr(III) was obtained using conductimetric detection in 12min. The method was successfully applied to the simultaneous determinations of Cr(VI) and Cr(III) added into tap-water and river-water samples. 2010 © The Japan Society for Analytical Chemistry.