Graphene oxide-silica composite coating hollow fiber solid phase microextraction online coupled with inductively coupled plasma mass spectrometry for the determination of trace heavy metals in environmental water samples.

In this work, a novel graphene oxide-silica (GO-silica) composite coating was prepared for hollow fiber solid phase microextraction (HF-SPME) of trace Mn, Co, Ni, Cu, Cd and Pb followed by on-line inductively coupled plasma mass spectrometry (ICP-MS) detection. The structure of the prepared graphene oxide and GO-silica composite was studied and elucidated by atomic force microscopy (AFM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). The GO-silica composite coated hollow fiber was characterized by scanning electron microscope (SEM), and the results show that the GO-silica composite coating possessed a homogeneous and wrinkled structure. Various experimental parameters affecting the extraction of the target metal ions by GO-silica composite coated HF-SPME have been investigated carefully. Under the optimum conditions, the limits of detection (LODs, 3σ) for Mn, Co, Ni, Cu, Cd and Pb were 7.5, 0.39, 20, 23, 6.7 and 28 ng L(-1) and the relative standard deviations (RSDs, c(Mn, Co, Cd)=0.05 μg L(-1), c(Ni, Cu, Pb)=0.2 μg L(-1), n=7) were 7.2, 7.0, 5.6, 7.3, 7.8 and 4.6%, respectively. The accuracy of the proposed method was validated by the analysis of Certified Reference Material of GSBZ 50009-88 environmental water and the determined values were in a good agreement with the certified values. The proposed method has been successfully applied for the determination of trace metals in real environmental water samples with recoveries ranging from 85 to 119%.