SPECIATION OF CR(III) AND CR(VI) BY REVERSED-PHASE HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY USING UV-DETECTION

A method for the simultaneous determination of Cr(III) and Cr(VI) in w ater samples is described. The different reaction products of Cr(III) and Cr(VI) species with ammonium pyrrolidinedithiocarbamate (APDC) are extracted with ethyl acetate and determined by reversed phase HPLC us ing UV-detection. The procedure is optimized and its detection limit a ccordingly improved as compared to literature data. The detection limi ts achieved are 2.4 mug/l for Cr(III) and 2.1 mug/l for Cr(VI) and the calibration curves are linear between 5 mug/l and 5000 mug/l. For the speciation of Cr, APDC was demonstrated to be more suitable as chelat ing agent than sodium diethyldithiocarbamate (NaDDC). The procedure wa s applied to the determination of both Cr species in galvanic waste wa ters and its accuracy was approved by comparing the results (at the 10 0 mug/l level) with those of a photometric determination of Cr(VI) spe cies.