Rationale behind the optimum efficiency of columns packed with new 1.9 μm fully porous particles of narrow particle size distribution

Columns packed with new commercially available 1.9 fully porous particles of narrow particle sizedistribution (nPSD) are characterized by extremely high efficiency. Under typical reversed phase con-ditions, these columns are able to generate very high number of theoretical plates (in the order of300,000 plates/m and more). In this paper, we investigate the origin of the high performance of thesenPSD columns by performing a series of measurements that include, in addition to the traditional deter-mination of the van Deemter curve, peak parking, pore blocking and inverse size exclusion experiments.Two nPSD columns (both 100 × 3.0 mm) have been considered in this study: the first one, packed withparticles of 80˚A pore size, is commercially available. The second one is a prototype column packed with1.9 fully porous particles of 120˚A pore size.The main conclusion of our study is that these nPSD columns are characterized by extremely low eddydispersion, while longitudinal diffusion and mass transfer kinetics are substantially equivalent to thoseof other fully porous particles of similar chemistry