Multivariate Optimization of a Functionalized SBA-15 Mesoporous Based Solid-Phase Extraction for U(VI) Determination in Water Samples.

A solid-phase extraction based on a functionalized SBA-15, with the Schiff base ligand, ethylenediaminepropylesalicylaldimine (SBA/EnSA), was developed for the recovery and preconcentration of trace amounts of uranium(VI) in water samples, prior to its determination spectrophotometrically using ArsenazoIII. For optimizing the parameters affecting the adsorption step (pH, adsorbent dose and adsorption time) and those influencing the desorption process (concentration and volume of eluent and desorption time), a statistical technique response surface methodology (RSM) was employed. The limit of detection and the linear dynamic range for the proposed method were 10 μg L-1, and 33.5 - 500 μg L-1, respectively. The adsorbent showed a high capacity (110.2 mg g-1) and the method allowed obtaining a preconcentration factor of 67. The inter- and intra-day relative standard deviations for a solution of 100 μg L-1 (n = 5) were found to be 4.8 - 6.2%. The developed method was successfully applied for the determination of U(VI) in water samples.