Magnetic dispersive solid phase extraction based on polythiophene modified magnetic graphene oxide for mercury determination in seafood followed by flow-injection cold vapor atomic absorption spectrometry

Abstract

A new and efficient sorbent was introduced for magnetic dispersive solid phase extraction via oxidative polymerization of thiophene on the surface of magnetic graphene oxide. The sorbent was used for the extraction of mercury at trace levels in different seafood samples. Mineralization of the samples was carried out by microwave assisted digestion. Flow-injection cold vapor atomic absorption spectrometry was used for analysis of extracts. Scanning electron microscopy (SEM), energy-dispersive X-ray analyzer (EDX) and Fourier transform-infrared (FT-IR) were applied to characterize the prepared nanoparticles. Central composite design was applied to find the optimum values of adsorption and desorption parameters affecting the extraction efficiency. The optimum conditions were obtained as extraction time of 21 min; 20.0 mg sorbent in 50 mL of the sample solution with pH of 6.5, and elution with 2.5 mL of HCl 1.7 mol L⁻¹ under fierce vortex for 2.0 min. Under the optimal conditions, the preconcentration factor of 17 and extraction recovery of 85% were obtained. The limits of detection and quantification were found to be 0.025 ng mL⁻¹ and 1.0 ng mL⁻¹, respectively. The calibration curve was in the range of 1.0–85 ng mL⁻¹ with the coefficient of determination (R²) of 0.9997. The relative standard deviations (RSD%) for intra- and inter-day precisions were 4.0% and 9.98%, respectively. Finally, the proposed method was successfully applied to determine mercury in seafood samples.