Simultaneous determination of chromium(III) and chromium (VI) with reversed-phase ion-pair high-performance liquid chromatography

Abstract

A reversed-phase ion-pair high-performance liquid chromatographic method for the simultaneous determination of Cr^III and Cr^VI in aqueous solution was developed. Chromium(III) was chelated with ethylenedi-aminetetraacetic acid (EDTA) prior to the analysis. A C₈ column was used to separate the Cr^III–EDTA complex from the Cr^VI ions using an eluent containing acetonitrile and tetrabutylammonium ion. The separated species were monitored at 242 nm using an ultraviolet (UV) detector. The factors affecting complex formation, the chromate stability and prospective interferences were investigated. The proposed method provides a simple analytical procedure for Cr speciation. The detection limits were 0.4 ng for Cr^III and 1.6 ng for Cr^VI with a 20 µl injection. The relative standard deviations for Cr^III and Cr^VI were 0.24 and 1.78%, respectively.