Ricerc@Sapienza

Three columns packed with 2.0 ?m superficially porous particles, 1.7 ?m fully porous particles, and monodisperse 1.9 ?m fully porous particles with narrow particle size distribution have been deeply characterized from a kinetic point of view. The 1.9 ?m column showed excellent kinetic performance, comparable to that of the superficially porous one. These two columns also exhibit flatter c-branches of the van Deemter curve compared to the 1.7 ?m fully porous particles column, resulting in smaller loss of efficiency when they are operated at higher flow rates than the optimal ones. The independent evaluation of each contribution to band broadening has revealed that the difference in kinetic performance comes from the very small eddy dispersion contribution on the 1.9 ?m column, surprisingly even lower than that of the superficially porous one. This finding suggests a very good packing of the monodisperse 1.9 ?m column. On the other hand, the potential of 1.7 ?m fully porous particles is completely broken down by the strong frictional heating effect already arising at relatively low flow rates.