Magnetic solid-phase extraction with copper ferrite nanoparticles for the separation and preconcentration of ultra-trace amounts of tellurium (IV) ion in aqueous samples

Abstract

A selective, simple and rapid magnetic solid-phase extraction was developed using copper ferrite (CuFe2O4) as an efficient sorbent for the separation and preconcentration of tellurium (IV) ion prior to its determination by electrothermal atomic absorption spectrometry. In this method, only 5 mg of the sorbent was needed to obtain a satisfactory extraction recovery. The CuFe2O4 was synthesized by means of a simple coprecipitation method and subsequently characterized by X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy. The factors affecting the separation and preconcentration of tellurium (IV) ions including, the type of desorption solvent, desorption solvent concentration and volume, desorption temperature and time, pH, amount of sorbent, extraction temperature and time were investigated and optimized. The effects of interfering ions on the extraction of Te (IV) ions were also investigated. Under the optimized conditions, the method exhibited a linear dynamic range of 0.04–0.5 µg L−1 with good linearity (r2 = 0.9982). The limit of detection and sorption capacity were found to be 0.012 µg L−1 and 89.0 mg g−1, respectively. Enrichment factor was 223. The intraday, interday, and batch-to-batch relative standard deviations were found to be 3.1, 4.4, and 6.0% for 0.25 µg L−1 concentration. Finally, the proposed analytical procedure was successfully applied to monitor tellurium (IV) ions in some aqueous samples, with relative recoveries of > 96%.