Magnetic dispersive micro-solid-phase extraction using Fe3O4@AC-DZ nanosorbent for the determination of Cr(VI) in water samples

A selective, sensitive, simple, and fast method for pre-concentration and determination of trace amounts of Cr(VI) in an aqueous solution was developed. Fe3O4 magnetic functionalized activated carbon modified with dithizone (Fe3O4@AC-DZ) nanoparticles as an adsorbent was synthesized and characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and vibrating sample magnetometer (VSM). The sorbent was employed in dispersive micro solid-phase extraction (D-mu SPE) of Cr(VI) from aqueous samples. Then, the analyte was desorbed by NaOH solution at pH = 10 and determined spectrophotometrically using diphenylcarbazide reagent. Some significant factors influencing extraction of the analyte were examined and optimized. Under the optimum conditions, the linear concentration range was 10-5000 mu g L-1 Cr(VI) with a limit of detection and limit of quantification 8.3 and 27.4 mu g L-1, respectively, with the preconcentration factor of 9. The relative standard deviation for five replicate measurements of Cr(VI) concentration at 100 mu g L-1 was 3.0%. Also, the efficiency of the extraction method in the presence of interfering ions was investigated. The proposed method was successfully applied to the determination of Cr(VI) in four type of water samples.