Automatic chromium (III)/(VI) preconcentration and speciation by flow injection-flame AAS

A sensitive, rapid flow injection flame AAS method for the simultaneous determination of Cr(III) and Cr(VI) following ion-exchange preconcentration is proposed. Chromium(III) is separated and preconcentrated on a cation-exchange resin, Amberlite IR-120, and Cr(VI) on Amberlite IRA-400. Preconcentration parameters (column size, eluent, loading and elution flow rate) were optimized, and the phase transfer, retention and enrichment factor for both species determined. The linear dynamic ranges achieved were 0-1000 mu g/L for Cr(III) and 0-900 mu g/L for Cr(VT), with a relative standard deviation of 4.4% and 7%, respectively. The detection limits obtained were 14.3 and 1.4 mu g/L for Cr(III) and Cr(VI) respectively. The proposed method was applied with good results to the determination of both analytes in water samples from chrome-plating baths.