Magnetic dispersive solid phase microextraction for the separation and quantification of brilliant green in various water samples

This work reports preparation and application of reduced graphene oxide-cobalt oxide (rGO-Co3O4) nanocomposite [1,2] as selective and regenerable magnetite sorbent for the preconcentration and determination of brilliant green (BG) by UV-Vis spectrophotometry. The properties of the graphene/Co3O4 nanocomposite were characterized by UV-visible spectrophotometry, Fourier-transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), and field emission scanning electron microscopy (FE-SEM). Magnetic dispersive solid phase microextraction (MD-SPME) [3], as a green, simple and sensitive method has been proposed for separation and preconcentration of trace quantities of BG. The ferromagnetic properties of the synthesized nanocomposite allowed effective separation and recyclability of the material by simple application of an external magnet. The experimental parameters affecting the MD-SPME efficiency for the target analyte including sample pH, brilliant green concentration, adsorbent dose and shaking time were investigated and optimized by central composite design coupled with desirability function approach [4]. Under the optimized conditions, the enrichment factor was 33. The detection limit and relative standard deviation (RSD) were 2.8 ng mL−1 and 1.3% (n=5) respectively. Finally, the applicability of the proposed method was successfully evaluated by determination of trace amounts of BG in various water samples.