Magnetic iron-cobalt/silica nanocomposite as adsorbent in micro solid-phase extraction for preconcentration of arsenic in environmental samples

A new method for separation/preconcentration of trace As in environmental samples by micro solid-phase extraction (μ-SPE) using CoFe₂O₄@SiO₂ magnetic nanoparticles (MNPs) prior to ICP-OES determination, has been developed. The morphological characteristic of the magnetic nanomaterial was characterized by scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM-EDS), and X-ray diffractometer (XRD). Optimal experimental conditions including pH, adsorbent mass, and eluent acid concentration were found to be 3, 100 mg and 5 mol L^-1 HCl, respectively. The adsorption capacity of the MNPs of As was found to be 8.5 mg g^-1. Under optimum conditions, the analytical limits of detection (LOD) and limits of quantification (LOQ) were found to be 2.8 and 9.2 μg L^-1, respectively. The accuracy of the method was tested by analyzing certified wastewater (CWW-TM-D) and the recoveries were found to be greater than 90%. The method was successfully applied to the determination of trace amounts of As in river and tap water samples.