Chemically modified a magnetic graphene oxide nanoparticles based micro solid phase extraction for effective pre-concentration of highly toxic metal ions from food stuff sample

With the rapid development of industrialization, heavy metal contamination has become an important environmental problem, that leading to serious health problems for human beings[1]. There are various methods for separation of the metal ions. The SPE method has been very much considered among of the available methods. On the other hand, the nature of the adsorbent in SPE effectiveness is so important. So far, various carbon-based nanoadsorbents including graphene oxide (GO), carbon nanotubes (CNT), and activated carbon (AC) have been provided, and their use on a variety of environmental pollutants have been investigated. Graphene oxide (GO) has attracted more attention in recent years. GO contains various effective functional groups such as hydroxyl, carboxyl and epoxy to combine with heavy metals to efficiently adsorb heavy metals[2]. However, time-consuming separation of GO is as a problem (due to the use of centrifuge step). In order to improve performance of GO-based adsorbents, usually, the GO surfaces were modified. In the current research, for the first time a magnetic graphene oxide (GO-Fe3O4-DA) modified with dopamine (DA) was successfully synthesized. Fe3O4 nanoparticles were selected for two purposes: i) easy separation of adsorbent from soluble target analyte ii) graphene oxide connection to the surface of Fe3O4 nanoparticles as a functional group for increasing the metal ion adsorption[3]. The structure of the synthesized nano-adsorbent was confirmed by XRD, SEM, FT-IR and VSM analysis. In this work a new method based on SPE was used to enhance the interactions in the shortest possible time. This technique named “effervescent-assisted dispersive micro solid-phase extraction (EA-Dµ-SPE). in this method was used the dispersant reagents in the sample solution, that lead to increased interactions of adsorbent with analyte and decreased of extraction time. Eventually, the extraction ions were quantified by micro sampling-flame atomic absorption spectrometry ( µS-FAAS). The limits of detection (LODs) was obtained 0.5, 0.03 and 0.7 μgL−1 for Pb(II), Cu(II) and Ni(II), respectively. Also, the relative standard deviations (%RSDs, for n = 3) was obtained 1.09%,1.25% and 1.03% for Pb(II), Cu(II) and Ni(II), respectively. This method was also applied successfully for the simultaneous detection of the Pb(II), Cu(II) and Ni(II) ions in the real samples of water and sausages (herbal and meaty).