On-Line Simultaneous Sorption Preconcentration and Determination of Chromium(III) and Chromium(VI) with AAS Detection

Speciation and simultaneous preconcentration of Cr(III) and Cr(VI) is based on the sorption of the reaction product of Cr(III) with Chromazurol S in weakly acidic solution and the sorption of the reaction product of Cr(VI) with sodium diethylcarbamate in strongly acidic solution. Reversed C18 phase was used for sorption of both the products. Both the complexes were eluted from columns directly into an AAS nebulizer using methanol. All the processes were automated. This method can be used for initial concentrations of Cr(III) and Cr(VI) below 1 ppm. The detection limits were 0.2 μg l-1 for Cr(III) and 2.4 μg l-1 for Cr(VI). This method was tested for analysis of practical samples (drinking and surface waters and soil extracts).