Speciation of Cr(III) and Cr(VI) in potable waters by using activated neutral alumina as collector and ET-AAS for determination

The speciation of Cr(III) and Cr(VI) has been performed by using activated neutral alumina as adsorbent. Both species were quantitatively adsorbed on a small column filled with neutral alumina. The adsorbed Cr(III) was eluted with 4 mol L-1 HNO3 and Cr(VI) with 1.0 mol L-1 ammonia solution. Recoveries of Cr(III) and Cr(VI) were 99% and 100%, respectively. Using ET-AAS for Cr determination the limit of detection in the sample was 0.01 mug L-1. The combined procedure is fast and sensitive. It can be applied for routine analysis of water samples at sub-mug L-1 levels with a relative standard deviation (RSD) of 2-10% (three determinations).