Synthesis Of Monolith Silica Column And Study On Chromatographic Separation Performance

Currently, chromatographic techniques have basically meet the needs of most related industries. However, in some areas, such as study on proteomics and biochemical separation, researchers have put forward higher requirements to chromatographic techniques, and they have committed to the preparation of columns, with higher selectivity, higher column efficiency and faster separation. As a new pattern monolith, silica monolith, with high permeability, high mechanical strength and rapid separation, etc., draw more attentions of scientists. But the preparation process of column was very complex and time-consuming. In addition, the reproducibility of column was poor, and it was easy to crack during drying and roasting.In the present thesis, using tetramethoxysilane(TMOS) and vinyl trimethoxysilane(VTMS) as precursors, silica monoliths were synthesized by sol-gel method with simple preparation process and short cycle. During the sol-gel experiment, the impacts of various reaction parameters on the structure of columns were investigated, and the optimum dosage was selected. At high temperature, the columns were treated by ammonia with different concentrations to fabricate nano-pores; In the drying process of wet columns, N,N-dimethylformamide was added in order to effectively reduce the phenomenon of cracking. The results show that, silica monoliths prepared under optimum conditions were not easy to crack, with uniform holes structure and high permeability; The monolithic silica columns bed were wrapped with epoxy, filling into the 5cm in length, 4.6mm in diameter stainless steel columns, in the liquid chromatograph(Shimadzu LC-10AD), under the normal phase chromatography mode, they can efficiently separate benzene from the mixture.After acidification by hydrochloric acid, monolithic silica columns were modified by N,N-dimethyldodecylamine(DMDA). The Experiments discussed the best conditions of monolith columns surface modified by DMDA. By infrared spectroscopy, the change of structure before and after bonded was detected. Finally, the chromatographic separation performance of the monolith columns was studied. The results showed that, N,N-dimethyldodecylamine can be bonded to the surface of the monolithic silica column, to achieve effective separation of benzene and substituted benzene in the revered phase chromatography mode.In addition, the monolithic silica capillary column 50 cm in length was successfully prepared from tetramethoxysilane(TMOS) and trimethoxysilane(VTMS). To improve the capillary wall effect was one key step to the preparation of monolithic silica capillary column. Selecting appropriate reagent to pre-treat capillary wall, which could effectively reduce the capillary wall effect. During the sol-gel experiments, the impact factors of the monolithic silica capillary columns structure were investigated, including the different ratio of TMOS/VTMS? PEG dosage as well as different methods to fabricate holes. The results showed that, when the ratio of TMOS/VTMS was 4:1, the monolithic silica capillary columns with good structure were prepared. The pores size were uniform, and through holes size 2.4?m, skeleton size 1.6?m, hole size/frame sizes up to 1.5, the column had high permeability.