Preconcentration of mercury(II) using a magnetite@carbon/dithizone nanocomposite, and its quantification by anodic stripping voltammetry.

A new adsorbent is described that consists of a magnetite@carbon/dithizone nanocomposite. It was characterized using energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and field emission scanning electron microscopy. The magnetic sorbent is shown to be a viable material for the preconcentration of mercury(II) before its quantification by differential pulse anodic stripping voltammetry. The effects of pH value, eluent, adsorbent amount, sample volume, and adsorption/desorption time were optimized. The calibration plot extends from 0.25 to 30 ng.mL-1, and the detection limit is 27 pg.mL-1. The preconcentration factor and intra-day and inter-day relative standard deviations are 100, 3.8, and 4.5%, respectively, for six measurements at 5 ng.mL-1 concentrations of mercury(II). The method was validated by the analysis of the certified reference material NIST SRM 1566b, and successfully applied to the preconcentration and quantification of mercury(II) in industrial wastewaters and spiked water samples. Graphical abstractSchematic representation of magnetic solid-phase extraction of mercury(II) ion by dithizone-modified Fe3O4@C nanocomposite (Fe3O4@C/Dz NC) before its quantification by anodic stripping voltammetry (ASV).