| Since the first report on the synthesis of the novel M41S silica mesoporous materials (particularly MCM-41) by Mobil researches in 1992, much attention has been paid to these materials. These mesoporous materials not only posses extremely high surface areas, well-defined pore structures, and huge pore volume, but also have higher mechanical and chemical stability. Owing to these desirable characteristics, mesoporous silica materials and functionalized mesoporous materials have been widely used as catalytic, sorbents and separation. As a novel inorganic or inorganic/organic functional material, the material has potential applications in the many fields.Solid-phase microextraction (SPME) is a novel solvent-free extraction technique that integrates extraction, concentration and sample introduction in a single step. It has advantages of simplicity, rapid extraction, and easy quantification. SPME has also been interfaced with gas chromatography (GC) and high performance liquid chromatography (HPLC) and other apparatus, and successfully applied to the analyses of various compounds in the environmental, food and clinical samples.The fiber coating is its active site contacting analytes of interest. The property of the coating determines the extraction capacity, sensitivity, selectivity and the results of analysis. Currently, the general applications for SPME are devoted to fused silica fibers coated with various polymeric coatings such as polydimethylsiloxane (PDMS) and polyacrylate (PA). To improve the sensitivity and selectivity of SPME technique, ion-exchange coatings, carbowax coatings, Nafion coatings, graphitized carbon black, porous activated charcoal and chemically bonded stationary phase have been developed as the fiber coatings of SPME. With the development of these novel coatings, the SPME technique has a wide application in extraction and separation.This thesis consists of five parts:Chapter 1 reviews the current state of the art in mesoporous material research and introduces its synthesis simply according to different channel structure, shape morphologies,also including its derivation production. The emphasis is placed on its applications in the fields of adsorption and separation.Chapter 2 covers the current SPME technique and the development of SPME fiber coating.In Chapter 3, using trimethoxyphenysiliane as a silanized reagent, one-spet synthesis of mesoporous materials (C6H5-MCM-41) was employed under alkaline reaction conditions. The as-synthesized mesoporous composite was characterized by small angle XRD, FT-IR, DTA, SEM, nitrogen adsorption-desorption, elemental analysis and titration. High extraction efficiency of benzo[a]pyrene is obtained using phenyl-functionalized mesoporous materials as solid-phase microextraction fiber coating.In Chapter 4, the C6H5-MCM-41 was employed as the new fiber coating of SPME coupled with HPLC. The performance of the fiber coating was characterized by the effect of extraction and desorption time, extraction temperature, stirring rate and ionic strength for determination of PAHs. The linear range, detection limit, recovery and reproducibility were investigated, and the results were satisfactory. A fast, convenient, precise, sensitive and suitable method was established for the determination of PAHs in environmental samples.In Chapter 5, MCM-41 typed mesoporous hybrid was investigated as the fiber coating of SPME compared with bonded porous silica by extracting four compounds in combination with HPLC. It was found that mass transfer from bulk solution to the mesopores is diffusion controlled in extraction process, especially for phenyl-functionalized mesoporous hybrids. MCM-41 coating has greater extraction capacity, higher sensitivity, better reproducibility and selectivity than bonded porous silica coating at the same time. |
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