Multi-Element Determination of Toxic and Nutrient Elements by ICP-AES after Dispersive Solid-Phase Extraction with Modified Graphene Oxide

A novel graphene-oxide-derived material was synthesized after modification of graphene oxide with sodium hydroxide and used for the dispersive solid-phase extraction (d-SPE) of different elements (Pb, Cd, Ba, Zn, Cu and Ni) prior to their determination by inductively coupled plasma atomic emission spectrometry (ICP-AES). The prepared nanomaterial was characterized by X-ray diffraction (XRD), nitrogen adsorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier transform infrared (FTIR) spectroscopy. Full factorial design and Derringer’s type desirability function were used for the optimization of the d-SPE procedure. Pareto charts illustrated the effects of each of the examined factors and their interactions on the determination of the elements. Under the optimum conditions, detection limits (LODs) for the elements ranged between 0.01 and 0.21 μg g−1, intra-day repeatability (n = 5) was lower than 1.9% and inter-day repeatability (n = 5 × 3) was lower than 4.7%. Relative recovery values ranged between 88.1 and 117.8%. The method was validated and successfully applied for the determination of trace elements in poultry, pork and beef samples from the local market. The proposed method is simple, rapid, sensitive and the novel sorbent can be used at least ten times.