“Preparação de fases estacionárias monolíticas em capilares revestidos com poliacrilato para aplicação em eletrocromatografia capilar”

Abstract

This dissertation describes monolithic stationary phase (MSP) photo-initiated polymerization in polyacrylate-coated fused silica capillaries using a sol-gel approach. The objective of this study was to contribute for implementation of Capillary Electrochromatography (CEC) at Juiz de Fora Federal University (UFJF). Chapter 1 briefly describes CEC, relating it with Capillary Electrophoresis (CE) and High Performance Liquid Chromatography (HPLC). General features about stationary phases, including monolithic columns, are discussed. Chapter 2 presents reagents, solutions, materials, equipments and methods used for the preparation, evaluation and application of the monolithic columns, as well a brief discussion about the sol-gel approach. Some parameters related with preparation and optimization of the monolithic columns are discussed in Chapter 3. In general, MSP preparation steps are simple. The polyacrylate coating, unlike the polyimide one, is transparent to the applied radiation, making the photo-initiated polymerization approach possible, without coating removal. Moreover, this feature makes the visualization during filling process as well observation of the obtained MSP easy. Chapter 4 shows results obtained for quality evaluation of the MSP taking into account permeability, mechanical resistance and electrochromatographic properties. The solvent quantity used for sol preparation is related with the permeability of the MSP obtained. The electrochromatographic behavior was tested by means of separation of a standard mixture containing propylbenzene, phenanthrene and pyrene in monolithic columns with a 125 µm internal diameter. Chapter 5 describes the UV-Vis chamber assembly equipped with black and white fluorescent lamps used for the photo-initiated polymerization. Some advantages of this homemade photochemical reactor are the following: low-cost (about US$ 150.00), taking into account that all parts can be easily purchased in the local market; simple adaptations can be done in accordance with convenience and the purposes of the system; the bottom part is mobile, so the sample can be placed at different heights from the emission sources. The chamber assembly showed in this work is a great alternative for groups interested in this kind of instrument which do not have many financial resources. In Chapter 6, the aspects and conclusions obtained during project execution are discussed. Appendix A shows some experimental results obtained for the preparation of MSP by thermal polymerization.