Synthesis Of Functionalized Mesoporous Materials And Their Applications In Solid-phase Microextraction

Human life is based on various materials. The chosen material of a given area is often its defining point. Their developments are closely related to the human civilization. Currently porous materials have extensively been used in many industrial fields because of their unique structure and large surface area. Order mesoporous material series is a novel family member of porous materials. For more than one decade, great attention has been paid to these materials with larger surface area and wall thickness, uniform pore size distribution, huge pore volume and higher thermal and hydrothermal stability with respect to the microporous materials. For these reasons, a study on mesoporous materials has become one of frontier field in chemistry, physics and materials science.Solid-phase microextraction (SPME) was developed on the basis of solid-phase extraction in the early 1990s as a novel solvent-free extraction technique in sample preparation. It is simple, convenient, rapid and highly sensitive and has been successfully applied to preconcentration and determination of various analytes from various sample matrices such as environmental samples, biological samples, foods and pharmaceuticals coupled to gas chromatography (GC), high performance liquid chromatography (HPLC) and capillary electrophoresis (CE).Fiber coating is the key part of SPME. The extraction selectivity and the efficiency of the fiber greatly depend on the coating materials. Although the general fiber coatings of SPME are commercially available and meet with the requirement for extraction, the fused silica fibers with polymeric coatings have such disadvantages as easy fragility, low thermal stability, little selectivity for general-purpose polymers and swelling of polymers for direct contact of cross-linked polymers with organic solvent. As a result, new fiber coatings with high stability, good selectivity and high mechanical strength are needed to prepare and investigate in order to improve the extraction behavior of SPME, extend their applications and prolong the lifetime of the fiber coating. It is of great importance to develop novel fiber coatings for special demand in SPME.In this dissertation, great effort is to synthesize organic-inorganic mesoporous composites including SBA-15, HOM-2 and HOM-5 with phenyl groups and SBA-15 with methyl, propyl and octyl groups. These materials were employed as the fiber coatings of SPME and successfully applied to the determination of 8 PAHs in the environmental water samples by SPME/HPLC.The dissertation consists of six parts:In Chapter 1, the synthesis, the modification, characterization and applications of mesoporous materials are summarized. The theory and the technique of SPME are introduced briefly. The advances in SPME technique and the development of fiber coatings are reviewed.In Chapter 2, phenyl-functionalized mesoporous silica materials (Phenyl-SBA-15) were synthesized for the first time via direct method. Samples were characterized by Fourier transform infrared spectroscopy (FT-IR), small-angle X-ray diffraction (SAXRD), thermogravimetric analysis (TGA), N₂ adsorption-desorption, scanning electron micrography (SEM) and transmission electron micrography (TEM).In Chapter 3, different alkyl functionalized mesoporous silica materials (Methyl-SBA-15, Propyl-SBA-15, Octyl-SBA-15) were synthesized for the first time via direct method. Samples were characterized by FT-IR, SAXRD, TGA, N₂ adsorption-desorption, SEM and TEM.In Chapter 4, two kinds of novel phenyl-functionalized mesoporous silica materials (Ph-HOM-2 and Ph-HOM-5) were fabricated for the first time via instant-direct-templating method. Samples were characterized by FT-IR, SAXRD, TGA, N₂ adsorption-desorption, SEM and TEM.In Chapter 5, a SPME fiber with Ph-SBA-15 coating was examined for the determination of naphthalene, phenanthrene, anthracene and fluoranthene in different environmental water samples coupled to HPLC/UV. The experimental conditions of SPME such as extraction and desorption time, extraction temperature, stirring rate, salt concentration were studied and optimized.In Chapter 6, SPME with M-SBA-15, P-SBA-15 and O-SBA-15 fiber coatings was investigated for the determination of acenaphthene, fluorine, pyrene, and benzo[a]pyrene in different environmental water samples coupled to HPLC/UV. The experimental conditions of SPME such as extraction and desorption time, extraction temperature, stirring rate and salt concentration were optimized.