INTERFACING ION CHROMATOGRAPHY WITH INDUCTIVELY-COUPLED PLASMA-ATOMIC EMISSION-SPECTROMETRY FOR THE DETERMINATION OF CHROMIUM(III) AND CHROMIUM(VI)

Cr(III) and Cr(VI) can be separated and detected by ion chromatography (IC) with inductively coupled plasma atomic emission spectrometry (ICP-AES). This combined method gives reliable, reproducible results rather quickly. A measurement requires 3 min and a 50-mu l sample. ICP-AES was used as an element-selective detection method for IC. Two IC techniques were compared for separation. In the first case the eluent was 7.5 mM potassium hydrogenphthalate and in the second case eluent changing was used. The first eluent was water; the second was I M HNO3. The IC column was a Polispher AN anion exchanger. The Cr(VI) (CrO42-, Cr2O72-) is retained in the column while the Cr(III) passes through without any retention. The main advantages of ICP detection are: the first (eluent) peak -which contains the Cr(III)- can be evaluated and the element selectivity and sensitivity provides reliable results. These methods were used for measuring the water-soluble Cr(III) and Cr(VI) contents of contaminated soils. The detection limits of Cr(III) and Cr(VI) are 0.25 and 0.27 mu g/g, respectively.