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

• New sub-2 μm C18 fully porous particles with narrow particle size distribution (nPSD).
• Kinetic performance of nPSD columns is studied from a theoretical viewpoint.
• Excellent kinetic performance comes from very small eddy dispersion term.
• B- and C-term of van Deemter equation similar to those of fully porous C18 columns.

Columns packed with new commercially available 1.9 fully porous particles of narrow particle size distribution (nPSD) are characterized by extremely high efficiency. Under typical reversed phase conditions, these columns are able to generate very high number of theoretical plates (in the order of 300,000 plates/m and more). In this paper, we investigate the origin of the high performance of these nPSD columns by performing a series of measurements that include, in addition to the traditional determination 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 with particles of 80 Å pore size, is commercially available. The second one is a prototype column packed with 1.9 fully porous particles of 120 Å pore size.The main conclusion of our study is that these nPSD columns are characterized by extremely low eddy dispersion, while longitudinal diffusion and mass transfer kinetics are substantially equivalent to those of other fully porous particles of similar chemistry.