SIMULTANEOUS DETERMINATION OF COBALT AND CHROMIUM BY ION CHROMATOGRAPHY WITH CHEMILUMINESCENCE DETECTION AND ITS APPLICATION TO GLASS ANALYSIS

A method is described for the simultaneous determination of very low levels of Co and Cr by high performance ion chromatography coupled with a chemiluminescence detection system. 0.1 M K2SO4 solutions, adjusted to pH 3.0, were used as eluent to separate Co(II) and Cr(III) between them and from interferents. The detection system was the chemiluminescence of luminol/H2O2 in alkaline medium catalyzed by such transition metals. Using a matrix solution analogous to soda-lime silica glass (dissolved in acids) calibration graphs were linear up to 0.5 ng ml-1 for cobalt and up to 250 ng ml-1 for chromium. The corresponding calculated detection limits (3 s) in such matrix were 0.05 ng ml-1 and 15 ng ml-1 for Co and Cr, respectively. The relative standard deviations were 1.4% at 0.5 ng ml-1 Co level and 2.8% at the 200 ng ml-1 Cr level. No interferences were observed from the more common metals, particularly those present in glass samples. The ion chromatography/chemiluminescent method proposed has been successfully applied to the analysis of Co and Cr in glasses.