SIMULTANEOUS DETERMINATION OF CHROMIUM(III) AND CHROMIUM(VI) IN AQUEOUS-SOLUTIONS BY ION CHROMATOGRAPHY AND CHEMILUMINESCENCE DETECTION

A method for the simultaneous determination of chromium(III) and chromium(VI) in a flow system based on chemiluminescence was developed. A Dionex cation-exchange guard column was used to separate chromium(III) from chromium(VI), and chromium(VI) was reduced by potassium sulfite, whereupon both species were detected by use of the luminol-hydrogen peroxide chemiluminescence system. Linear calibration for both species was established over the concentration range 1-1000-mu-g l-1. The precision at the 20-mu-g l-1 level was 3.5% for chromium(III) and 3.3% for chromium(VI), respectively. The detection limit was 0.5-mu-g l-1 for both species. Data were in agreement with Zeeman-effect background corrected atomic absorption spectrometry measurements.