One-step fabrication of hydrophilic MIL-68(Al)/Chitosan-coated melamine sponge for vortex-assisted solid-phase extraction of parabens in water samples.

A novel vortex-assisted solid-phase extraction method based on MIL-68(Al)/Chitosan-melamine sponge column (or V-MIL-68(Al)/CS-SC-SPE) is presented in this paper. The MIL-68(Al)/Chitosan-sponge column was prepared by a simple infiltration method and a preparation process that does not consume organic solvents. Scanning electron microscopy was used to characterize the functionalized sponge columns, and the skeleton and pores of the melamine sponge were successfully modified with the coating material (MIL-68(Al) and chitosan). Chitosan was used successfully not only as an adsorption adjuvant material, but also as an adhesive in the preparation of MIL-68(Al)/CS coating sponge materials. The presented method was further combined with high performance liquid chromatography (HPLC) and used in the determination of trace parabens (including methyl-, ethyl-, propyl- and butyl-parabens) in environmental water samples. Several important factors that affect the extraction performance were investigated. Under the optimum conditions, the method was successfully used to detect the four kinds of parabens in different water samples (domestic water, lake water and river water). The limits of detection ranged between 0.21 and 0.50 ng/mL, and the relative standard deviations for all parabens were below 10.8%.