Synthesis of Silica Gel Chelated with Alizarin and 1-Nitroso-2-Naphthol for Solid Phase Extraction of Lead in Ground Water Samples

Silica gel chemically functionalized with alizarin (Si-AZ) and 1-nitroso-2-naphthol (Si-NN) was synthesized and characterized by FT-IR, N2 adsorption-desorption, SEM, and elemental analysis. The two chelators show adequate sorption properties for Pb (II) and are hence used as SPE sorbents prior to their determination with ICP-MS. Both chelators showed high sorption efficiency for the Pb (II) ion at pH 8. Batch experiments demonstrate that the synthesized resins could remove more than 95% Pb (II) out of solutions containing 100 μg/mL of the ion. At optimum conditions, the maximum adsorption capacities for S-TDI-AZ and S-TDI-NN for Pb (II) were 9.56 and 9.43 mg/g, respectively. Method development was performed to investigate the applicability of the chelating resins as packing materials for SPE using model solutions and real groundwater samples. The method detection limits of SPE were 0.0025 and 0.0026 μg/L with high precision (R.S.D. < 3%). The recoveries of spiked Pb (II) with ground water were 104.70 and 102.62%. The proposed method was successfully applied to the determination of Pb (II) in the groundwater by ICP-MS.