Separation and Preconcentration of Pb2+, Cd2+, and Cr3+ in Water Samples by Solid-Phase Extraction Using a Novel Ionic Liquid-Modified Silica Sorbent

Abstract

A new sorbent based on ionic liquid-modified silica has been developed for the determination of Cd 2+ , Pb 2+ , and Cr 3+ in water. Ionic liquid-modified silica was simply synthesized with a low-cost procedure and was considered an environmentally friendly material. Five materials, namely DL1 to DL5, were prepared from five ionic liquids, including N,N,N -trimethyl- N -hexadecylammonium and N -alkylpyridinium hexafluorophosphate, which were grafted onto silica gel. These materials were used to enrich the trace concentration of three metallic cations (Cd 2+ , Pb 2+ , and Cr 3+ ) in water samples, followed by the ICP-MS analysis. Among these sorbents, DL1@SiO 2 showed high efficient sorption. The detection limit of this method for Cd 2+ , Pb 2+ , and Cr 3+ was 0.173 μg L -1 , 0.046 μg L -1 , 0.185 μg L -1 and the relative standard deviation (RSD) was 6.1%, 23.2%, 19.7%, respectively. The procedure was applied to determine Cd 2+ , Pb 2+ , and Cr 3+ content in the tap water sample (Ho Chi Minh City) with satisfactory recovery from 74 to 100.8%.

Keywords: Solid-phase extraction, Ionic liquids, heavy metal ion, silica gel, water sample