Dispersive solid phase microextraction with magnetic graphene oxide as the sorbent for separation and preconcentration of ultra-trace amounts of gold ions

A selective, simple and rapid dispersive solid phase microextraction was developed using magnetic graphene oxide (MGO) as an efficient sorbent for the separation and preconcentration of gold ions. The MGO was synthesized by means of the simple one step chemical coprecipitation method, characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM). Gold ions retained by the sorbent were eluted using 0.5 mol L-1 thiourea in 0.1 mol L-1 HCl solution and determined by the flow injection flame atomic absorption spectrometry (FI-FAAS). The factors affecting the separation and preconcentration of gold were investigated and optimized. Under the optimized conditions, the method exhibited a linear dynamic range of 0.02-100.0 mu g L-1 with a detection limit of 4 ng L-1 and an enrichment factor of 500. The relative standard deviations of 3.2% and 4.7% (n=6) were obtained at 20 mu g L-1 level of gold ions for the intra and the inter day analysis, respectively. The method was successfully applied to the determination of gold ions in water and waste water samples as well as a certified reference material (CCU-1b, copper flotation concentrate). (C) 2015 Elsevier B.V. All rights reserved.