Preparation Of Sol-Gel PLOT Capillary Column

Today, gas chromatography (GC) has become the primary technique for analysis and separation of organic compounds, especially for volatile compounds. The gas chromatographic column can be considered the heart of gas chromatography. Gas chromatography is a separation method in which the components of a sample have indifferent partition between gas phase and stationary phase. Capillary open tubular columns were introduced in 1957 by M.J.E.Golay. These columns have a dramatic increase in separation capacity over conventional packed columns and extremely promote the application and development of gas chromatography.According to the principle of partition, the capillary columns can be divided into two types, including gas-liquid chromatography column and gas-solid chromatography column. We can use the term "wall coated open tubular" (WCOT) to specify columns in which the liquid phase is deposited directly on the silica tubular surface. Columns in which the coating is deposited on a surface that has been considerably extended by macro elongated crystal deposits or finely granular of polymer are termed "porous layer open tubular" (PLOT) columns. And the term " support coated open tubular" (SCOT) should be used in which the column wall has been coated with a mixture of finely divided solid and liquid phase. Although gas-solid chromatography is less popular than gas-liquid chromatography, it is nevertheless used in such important fields as isotope separation and alkanes mixtures determination, where it exhibits certain advantages over its gas-liquid counterpart.The research and development on chromatographic columns is a hot topic. Some special companies and research groups research for novel stationary phase, new technology of making columns, improving the performance of columns, and enlarging the application of column. Currently, the technique of making GC column has become proprietary arts holding by commercial companies. The technology for the preparation of gas-liquid open tubular columns consists of some major, individually executed steps:capillary surface treatment, deactivation, static coating, and stationary phase immobilization. The technology for the preparation of gas-solid open tubular columns consists of such major steps:selecting adsorbent suspension, dynamic coating adsorption layer, chemistry modified and solidifying. In above conventional approach, these operations are carried out in separate steps that make column fabrication a time-consuming work, furthermore, the using temperature of columns is always a problem requested by user.Sol-gel capillary column is a new type of column for gas chromatography, which is made by sol-gel technology. The sol-gel column technology was introduced by doctor Malik at Florida University. The sol-gel chemistry-based column technology for GC is described that effectively combines surface treatment, deactivation, coating, and stationary phase immobilization into a single step. In this new approach, a sol solution of appropriate composition which involves alkoxide-based precursor, a hydroxy-terminated stationary phase, a surface derivatizing reagent, and a catalyst is filled into a fused silica capillary, and than sol-gel reactions are allowed to go on inside the capillary for a controlled period. The reaction only need 15 min, and the preparation time can be controlled in one hour.In this dissertation, we have carried out some original studies as following: (1) A novel method was developed to prepare Al2O3 porous-layer open-tubular(Al2O3-PLOT) column based on the sol-gel chemistry. (2) A new method is described to prepare silica porous layer columns by using in-situ sol-gel synthesis technology. By the interaction of ethyl acetate and water glass solution the silica was synthesized on the inner surface of fused silica capillary.Three parts are included in the dissertationChapterâ… :(1) The development of GC column. It summarized the conventional capillary column preparation, principle, classes.(2) The sol-gel technology for capillary columns. It summarized the sol-gel technology concept, principle, and application for GC column.Chapterâ…¡:The preparation of Al2O3-PLOT column is finished through sol-gel column technology. The sol-gel solution comprised of tetraethyl orthosilicate(TEOS), hydrochloric acid(HCl)and suspension of aluminum oxide in ethanol. The column performance was evaluated by using C1-C5 hydrocarbons sample. Chapterâ…¢:The preparation of SiO2-PLOT column is carried out through sol-gel column technology. The sol-gel solution comprised of ethyl acetate and water glass solution. The column performance was evaluated by using chlorofluorocarbons, sulfur compounds, and light hydrocarbons C1-C4.