| Due to the components and distractors in environmental samples were complex and the level of analytes was low, so the environment samples were usually pretreated before analyzed. Liquid-liquid extraction (LLE) and solid-phase extraction (SPE) were the most often employed sample pretreatment techniques. Despite their widespread use, those methods were tedious, labor-intensive and consumed large amounts of organic solvents. Microextraction technology has the advantages of low organic solvent consumption and high extraction selectivity, so it has been recently developed to replace these conventional sample pretreatment techniques. Solid-phase microextraction is an innovative, solvent-free extraction technique which combines sampling, concentration, matrix removal and sample introduction into one step. Sample matrixs has little effect on solid-phase microextraction (SPME), the samples also can be directly extracted without pretreatment. Based on the characteristic of SPME mentioned above, it can be applied to detect organophosphate esters (OPEs) flame retardants in environmental water samples. Due to the physical-chemical properties of OPEs have big differences, conventional coating fiber can not well meet the requirements for their analysis, so new coating fiber required to be developed for the selective extraction of OPEs.In this study, the solid-phase microextraction fiber based on graphene oxide was prepared by sol-gel technology, coupled with GC-NPD, the fiber was applied for the determination of OPEs in aqueous samples for the first time. The main research contains are listed as following:1. The graphene oxide solid-phase microextraction fiber was coated on a modified stainless steel wire through sol-gel technique. The fiber was characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), fourier infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and N2 adsorption-desorption measurement (BET). The result showed that the fiber coating was homogeneously and densely coated on the stainless steel, the surface of the coating was rough, crinkled and porous and the thickness of the coating was approximately 10 μm. The coating also had a good thermal stability. Several parameters which could influence the extraction efficiency of SPME fiber such as the amount of GO, extraction time, extraction temperature, ionic strength, stirring rate, desorption time and the volume of the sample were optimized. The extraction times was also investigated. Under the optimized conditions, the analytes showed a good linear relationship between 10 to 1×105ng L-1 (R>0.992).Based on a signal-to-noise ratio (S/N) of 3, the LODs were in the range from 1.4 to 135.6 ng L-1.Coupled with gas chromatography (GC)-nitrogen phosphorus detector (NPD), the fiber was applied for the determination of OPEs in three water samples by HS-SPME, the obtained relative recoveries were in the range from 80.5% to 112.4% with RSDs less than 9.9%. The satisfying accuracy and precision proved that the proposed method can be applied to the determination of OPEs in environmental water samples.2. A novel graphene oxide/β-CD solid-phase microextraction fiber was coated on a modified stainless steel wire through sol-gel technique. The integrated use of graphene oxide and β-CD for the preparation of the SPME fibers would take the advantages of the both and possibly enhance the efficiency of the prepared fiber. The fiber was characterized by scanning electron microscope (SEM), fourier infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and N2 adsorption-desorption measurement (BET). The result showed that the fiber coating was successfully coated on the stainless steel, the surface of the coating was more rough and crinkled compared to graphene oxide fiber and the thickness of the coating was approximately 10 μm. The coating also had a good thermal stability. Under the optimized extraction and desorption conditions, a sensitive SPME-GC analytical method was established. The obtained result show that the analytes showed a good linear relationship between 10 to 1 x 105 ngL-1 (R>0.995). Based on a signal-to-noise ratio (S/N) of 3, the LODs were in the range from 1.1-60.4 ng L-1. Coupled with gas chromatography (GC)-nitrogen phosphorus detector (NPD), the fiber was applied for the determination of OPEs in three water samples by HS-SPME, the obtained relative recoveries were in the range from 82.1%-113.9% with RSDs less than 10.4%. The satisfying accuracy and precision also proved that the proposed method was robust and could be applied to the determination of OPEs in environmental water samples. |
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