Selective Determination of Selenium in Garlic, Mushroom and Water Samples by Chemically Modified Mesoporous Silica Solid Phase Coupled with ICP-OES

A selective sorbent for solid phase extraction (SPE), based on a chemically modified mesoporous silica (SBA-15), followed by inductively coupled plasma-optical emission spectrometry was used for extraction, preconcentration, and determination of selenium in water and food samples. The main parameters of SPE including pH, amount of mesoporous (solid phase), concentration of the eluent (desorption solvent), and equilibrium time were optimized by using a fractional central composite design (f-CCD). The optimum conditions were found to be 3.2 for pH, 21 mg for amount of the mesoporous, 1 mol l(-1) for eluent concentration, and 9 min for equilibrium time. Under the optimal conditions, the limit of detection (LOD) was 2.56 mu g l(-1). The linear dynamic range (LDR) was 5-1,000 mu g l(-1) with determination coefficient (R (2)) of 0.999. Relative standard deviation (C = 400 mu g l(-1), n = 5) was 3.84 %. The enrichment factor was 20. The maximum sorption capacity of the modified SBA-15 was 15 mg g(-1). The sorbent presented good stability, reusability, high adsorption capacity, and fast rate of equilibrium for sorption/desorption of selenium (IV) ions.