A discussion of the possible ways to improve the performance of silica monoliths using a kinetic plot analysis of...

Using kinetic plots to analyse the performance of some of the best silica monoliths found in the literature shows that the current generation of silica monoliths outperform particulate beds only in the high plate-number region (roughly N > 40000). The plots also reveal the existence of a so-called 'forbidden region' wherein no existing chromatographic support seems to be able to operate. To investigate several possible approaches to intrude this forbidden region, computational fluid dynamics simulations of the flow field and band-broadening characteristics of a simplified structural mimic of real silica monoliths were made for five different porosities (epsilon = 0.38, 0.49, 0.60, 0.72, 0.86). It was found that entering the forbidden region will necessitate new synthesis methods, yielding either a strong improvement of the structural homogeneity (if assuming constant domain size conditions) or a decrease of the domain size (if assuming constant homogeneity conditions).