Ultrasound assisted magnetic dispersive solid phase microextraction for Hg determination in fuel oils using inductively coupled plasma optical emission spectroscopy.

Mercury is considered a global pollutant, and its quantification in fuel oils remains a priority for public health and the ecosystem. Functionalized graphene oxide has gained popularity for heavy metal adsorption in various matrices. Herein we present a highly selective and efficient magnetic graphene oxide coated with gold (FeO/GO-Au) nano adsorbent and its application to a dispersive solid-phase microextraction of mercury in fuel oils. The synthesized FeO/GO-Au nanocomposite was characterized using Fourier Transform Infra-Red spectroscopy (FT-IR), powder X-ray diffraction (P-XRD), Scanning electron microscopy (SEM/EDS), Transmission electron microscopy (TEM), Thermogravimetric (TGA), Brunauer-Emmett-Teller (BET), and vibration sample magnetometer (VSM) analysis. The multivariate optimum conditions for the extraction method were 20 min, 30 mg, pH 7, and 1.75 mol/L, for adsorption time, sorbent mass, pH, and eluent concentration, respectively. Under the optimized conditions, the dynamic linear range of 0.1 to 100 µg/L (R = 0.999) was obtained. The limit of detection (LOD) and preconcentration factor obtained were 0.035 µg/L and 255, respectively. Intra- and inter-day precision of the method were calculated to be 3.5% and 4.0%, respectively. The newly developed method was successfully applied in real crude oil, diesel oil, gasoline, and kerosene samples. The environmental impact of the newly developed procedure was evaluated and a total score of 0.64 was obtained.