Structural analyses chromatographic mobility

Based on the previous analysis of the different transport phenomena, which determine the overall mass transport rate, the structure of the solid phase matrix is of extreme importance. In the case of any chromatographic process, the different diffusion restrictions increase the time required for separation, since any increase of the flow rate of the mobile phase leads to an increase of the peak broadening [12]. Thus, the improvement of the existing chromatographic separation media (column packing of porous particles) and hence the speed of the separation should enable the following tasks ... 

Such precise control of porous properties is expected to be very useful in the design of specialized CEC columns for separation in modes other than reversed-phase. For example, size exclusion chromatography (SEC) is an isocratic separation method that relies on differences in the hydrodynamic volumes of the analytes. Because all solute-stationary phase interactions must be avoided in SEC, solvents such as pure tetrahydrofuran are often used as the mobile phase for the analysis of synthetic polymers, since they dissolve a wide range of structures and minimize interactions with the chromatographic medium. Despite the reported use of entirely non-aqueous eluents in both electrophoresis and CEC [65], no appreciable flow through the methacrylate-based monoliths was observed using pure tetrahydrofuran as the mobile phase. However, a mixture of 2% water and tetrahydrofuran was found to substan-... 

Warmuth [34] when they adopted NPC for the analysis of supermolecules, such as hemicarcerplexes. Hemicarcerplexes are complexes formed with hemi-carcerand host and guest molecules. As shown in Figure 5-6, hemicarcerands possess a very hydrophobic structure with molecular weight over 2000 and is insoluble in protic solvents. A normal-phase HPLC method was developed using a silica column with dichloromethane and diethylether as the mobile-phase system. The authors demonstrate that the chromatographic retention of hemicarcerplexes is mainly dominated by its size. Furthermore, a linear relationship between the logarithmic retention factor and the size of the hemicarcerplexes was observed for linear guest molecules independent of their polarity. 

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