Methods for the preparation of capillary columns for gas chromatography
Sammanfattning: This thesis is dedicated to column technology, and describes methods for the preparation of efficient, well deactivated and durable capillary columns for gas chromatography.Problems associated with column preparation are discussed in conjunction with a brief literature survey of the most important contributions to column technology since the concept of capillary gas chromatography was first introduced by M.J.E.Golay in 1957.Methods of preparation reported are:- Chemical surface modification of the capillary tubing, using cyclic siloxanes at high temperatures.This modification resulted in a thermostable deactivation of surface hydroxyl groups. Surface characteristics, such as wettability, can be controlled by using cyclic siloxanes with different organic substituents.- Static coating using liquid butane as solvent for the stationary phase.With a liquified gas as solvent, the speed of evaporation is increased thus makes the static coating less time-consuming.- Immobilization of stationary phases by in situ cross-linking. Three different cross-linking techniques have been investigated :1. Heat induced condensation.2. Cross-linking with tetrachlorosilane.3. Free radical-initiated cross-linking using dicumyl peroxide. Highly stable columns were obtained and the merits of each method are discussed.
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