Preparation And Application Of Novel Type Functionalized Magnetic Nanoparticles For The Analysis Of Trace Organic Pollutants

Magnetic nanoparticles（MNPs） are provided with many merits such as good stability, easy synthesis, high surface area, facile separation by magnetic forces, as well as low toxicity and low cost, and therefore have been widely applied in environmental and material science. The use of magnetic Fe₃O₄ based particles has been of intense interest in the research of sample pretreatment because of their ease of preparation,ease of surface modification, and excellent dispersibility in aqueous solution. Magnetic particles with special functionalities bound onto the surface could be applied to extract the target analytes, and they can be easily and quickly isolated by applying an external magnetic field placed outside the extraction container. So the analytes could be extracted rapidly from large-volume samples, and the magnetic particles with adsorbed sample can be easily collected by using an external magnetic field placed outside of the extraction container without additional centrifugation or filtration of the sample, which makes sampling and collection easier and faster. What’s more, the magnetic particles may be reused or recycled. The contents of this research were summarized as follows:1. cholesterol-functionalized magnetic nanoparticles（Fe₃O₄@SiO₂@Chol） were prepared for the determination of polycyclic aromatic hydrocarbons（PAHs） in traditional Chinese medicine samples（TCMs） by high performance liquid chromatography（HPLC） coupled with fluorescence detection. The method was efficient, environmentally friendly, and fast. The solvent consumption of the proposed column is only half of the conventional column but with higher efficiency. Influencing factors, including sorbent amount, desorption solvent, sample volume and extraction time, were investigated in detail. Under the optimum conditions, good linearity（R2>0.9909） was obtained over the range of 5-400 ng/g, with limits of detection（LOD） 0.75, 0.50, 1.0, 0.56, 0.60, 0.84 and 0.80 ng/g for anthracene, fluoranthene, pyrene, chrysene, benz[a]anthracene, benzo[b]fluoranthene and benzo[k]fluoranthene, respectively.2. A novel type of magnetic nanoparticles, 3-fluorobenzoyl chloride functionalized magnetic nanoparticles（Fe₃O₄@SiO₂@FBC MNPs） was successfully synthesized. It was applied to the extraction and determination of perfluorinated compounds（PFCs） by ultra-high performance liquid chromatography with tandem triple quadrupole mass spectrometry（UHPLC-MS/MS）. Due to the fluorous-fluorous interaction, the magnetic nanoparticles displayed excellent extraction performance for 6 PFCs, including perfluoroheptanoic acid（PFHp A）, perfluorodecanoic acid（PFDA）, perfluorododecanoic acid（PFDo A）, perfluorotetradecanoic acid（PFTe DA）, perfluorooctanoic acid（PFOA） and perfluorooctane sulfonate（PFOS）.The UHPLC separation of PFCs was very quick and could be achieved within 6 min. Various factors that may influence the magnetic solid-phase extraction（MSPE） efficiency, such as sorbent amount, desorption solvent, extraction time, p H value of water samples and sample volume, were investigated in detail. Under the optimum conditions, the linear ranges of six PFCs were 0.25-25 ng/L with the limits of detection（S/N = 3） ranging from 0.01 to 0.06 ng/L. Finally, the method was successfully applied to different river water samples, and the recoveries were in the range of 89.3-111.3%. These results indicated that the prepared Fe₃O₄@SiO₂@FBC sorbents could efficiently enrich PFCs and that the proposed method is reliable.3. A fast magnetic solid-phase extraction method based on magnet added in the water was presented. The new method saved time of dumping water samples, elution program and filtration, which greatly accelerate the magnetic solid phase extraction, and the whole extraction procedure can be finished within several minutes. For extraction of perfluorinated compounds, a novel type of magnetic sorbent, 4-（trifluoromethyl）-benzoyl chloride functionalized magnetic silica nanoparticles（Fe₃O₄@SiO₂@TFBC） was prepared. It was used for magnetic solid-phase extraction（MSPE） of perfluorinated compounds（PFCs） from traditional Chinese medicine samples（TCMs） including lumbricus, sea otter and leech. The fluorous functionalized nanoparticles contributed to the high-efficient preconcentration of PFCs, due to the fluorous- fluorous interaction. Six kinds of PFCs were selected as model analytes, including perfluoroheptanoic acid（PFHp A）, perfluorodecanoic acid（PFDA）, perfluorododecanoic acid（PFDo A）, perfluorotetradecanoic acid（PFTe DA）, perfluorooctanoic acid（PFOA） and perfluorooctane sulfonate（PFOS）. Ultra-high performance liquid chromatography-tandem triple quadrupole mass spectrometry（UHPLC-MS/MS） was used for the fast and sensitive detection of the analytes after sample pretreatment. Transmission electron microscopy, X-ray diffraction, and Fourier transform infrared spectrometry were used to characterize the sorbents. The main influencing parameters, such as sorbent amount, desorption solvent, extraction time, and sample volume were investigated in detail. Under the optimum conditions, only 10 mg of sorbent was sufficient to extract PFCs. The linear ranges of six PFCs were 0.20-20 ng/L with the limits of detection（S/N = 3） ranging from 0.01 to 0.045 ng/L, and relative standard deviation in the range of 2.1-5.0%. Finally, the method was successfully applied to TCMs, and the recoveries were in the range of 82.0-105.0%. These results indicated that the proposed method based on Fe₃O₄@SiO₂@TFBC sorbents is a simple, fast, and sensitive tool for the analysis of PFCs in water samples.4. A novel type of magnetic sorbent, naphthyl functionalized magnetic nanoparticles（Fe₃O₄@SiO₂@Nap） was prepared, and successfully used for the magnetic solid-phase extraction（MSPE） of polycyclic aromatic hydrocarbons（PAHs） from river water samples. The analytes were finally determined by high performance liquid chromatography coupled with fluorescence detection（HPLC-FLD）. Six kinds of PAHs were selected as the model analytes, including fluorene（Flu）, fluoranthene（Fl A）, anthracene（Ant）, pyrene（Pyr）, benz[a]anthracene（Ba A）, benzo[b]fluoranthene（Bb F） and benzo[k]fluoranthene（Bk F）. Transmission electron microscopy（TEM）, vibrating sample magnetometer（VSM）, and Fourier transform infrared spectrometry（FT-IR） were used to characterize the sorbent. The main influencing parameters, including sorbent amount, desorption solvent, sample volume and extraction time, were investigated in detail. Under the optimum conditions, only 40 mg of sorbent was sufficient to extract PAHs from 150 m L sample. The linear ranges of seven PAHs were 0.5-100 ng/m L with the limits of detection（S/N = 3） ranging from 0.04 to 0.12 ng/m L. The repeatability was investigated by evaluating the intra- and inter-day precisions with relative standard deviations（RSDs） lower than 4.3%. Finally, the method was successfully applied to river water samples, and the recoveries were in the range of 89.6-106.8%.5. Phenyl and diphenyl functionalized core/shell structured magnetic nanoparticles were prepared, and have been applied to extract seven polycyclic aromatic hydrocarbons（PAHs） from traditional Chinese medicine samples, respectively. The two sorbents were compared regarding their extraction efficiency, and analytes being finally determined by high performance liquid chromatography coupled with fluorescence detection（HPLC-FLD）. Seven kinds of PAHs were selected as model analytes, including fluorene（Flu）, fluoranthene（Fl A）, anthracene（Ant）, pyrene（Pyr）, benzo[a]anthracene（Ba A）, benzo[b]fluoranthene（Bb F） and benzo[k]fluoranthene（Bk F）. Scanning electron microscopy（SEM）, thermogravimetric analysis（TGA）, and Fourier transform infrared spectrometry（FTIR） were used to characterize the sorbents. Several performance parameters such as sorbent amounts, desorption solvent, sample volume and extraction time were investigated in order to compare the extraction efficiency of the two sorbents. The results show that, diphenyl functionalized magnetic sorbent has better extraction efficiency, which was successfully applied to extract PAHs from three TCMs including Astragali radix, Gentianae macrophyllae radix, and Menthae haplocalycis herba, and the recoveries were in the range of 75.7-110.8%.