Preparation of ionic liquid-modified SiO2@Fe3O4 nanocomposite as a magnetic sorbent for use in solid-phase extraction of zinc(II) ions from milk and water samples

In this study, silica-coated magnetite nanoparticles modified with triethoxysilylpropylpyridinium hexafluorophosphate ionic liquid were synthesized and used as a sorbent for the solid-phase extraction and preconcentration of zinc ions from aqueous solutions. The structure and morphology of the synthesized nanosorbent were characterized by X-ray diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopy. After desorption with acidic ethanol, zinc was quantified by flame atomic absorption spectrometry. The experimental factors affecting the extraction/preconcentration of the analyte were investigated and optimized. Under the optimized experimental conditions, the calibration graph was linear in the concentration range of 0.5-15 ng mL(-1) (with an R-2 value of 0.998). The limit of detection and the preconcentration factor were 0.17 ng mL(-1) and 100, respectively. The relative standard deviation for six replicate determinations of 10 ng mL(-1) Zn was 2.3%. The method was validated by the successful analysis of a standard reference material (NIST SRM 1549; non-fat milk powder) and employed for the determination of zinc in several samples of water and milk, with recoveries in the range of 97.0-102.5% for the spiked samples.