Separation and preconcentration of Se(IV)/Se(VI) species by selective adsorption onto nanometer-sized titanium dioxide and determination by graphite furnace atomic absorption spectrometry

A simple and sensitive method for the selective determination of Se(IV) and Se(VI) in natural water and sludge samples through an adsorptive process on a nanometer-sized TiO2 (anatase) was developed. The conditions for quantitative and reproducible preconcentration, elution, and subsequent GFAAS determination were established. The proposed method gave a concentration factor of 50 for a 100 mL sample volume, characterized by high precision, high reproducibility, and direct determination of Se(IV)/Se(VI). The detection limits (3 sigma, n=11) were 4.7 ng L-1 for Se(IV) and 6.3 ng L-1 for Se (VI); the precision (relative standard deviation) was 0.7% for Se (IV) and 0.9% for Se (VI) at the 0.5 mu g L-1 level.