Fractional Determination of Chromium(III) and Chromium(VI) via Ion Chromatography with Inductively Coupled Plasma Atomic Emission Spectrometric Detection

Abstract

A technique for the determination of Cr(lll) and Cr(VI) species is described which is based on an on-line ion chromatographic separation-inductively coupled plasma atomic emission spectrometric detection (IC-ICPAES). Improved sensitivity and shortened retention time of Cr(VI) are attained by the complex formation of Cr(li!) to tetrathiocyanatochromate(lll) anion prior to injection and the combined use of a short column (4.0 mm I.D.xlO mm) packed with a porous polyacrylate-based anion exchange resin and an eluant of a 5.0x10^-4 mol dm^-3 potassium hydrogen phthalate solution (pH 6.5). The ICPAES is used as a selective detector by observing chromium emission at 283.563 nm. Detection limits are 7.5 ng for Cr(lll) and 22 ng for Cr(VI). For a typical sample injection volume of 100 mm³ these detection limits correspond to 75 ng cm^-3 for Cr(lll) and 220 ng cm^-3 for Cr(VI) in concentration. This method can be applied to the fractional determination of Cr(lll) and Cr(VI) in waste water samples.