Kinetic plot and particle size distribution analysis to discuss the performance limits of sub-2 μm and supra-2 μm particle columns

To contribute to the current debate about the “ideal” particle size range (sub-2 μm vs. supra-2 μm), the present study compares the kinetic performance of some commercially available sub-2 μm and 3.5 μm particles used under quasi-adiabatic conditions via the kinetic plot method. Under the adopted assumption that viscous heating effects can be neglected (which is uncertain in a pressure range above 400 bar), the obtained kinetic plots show that, provided each particle size is used in a column with properly optimized length, the gain in separation speed that sub-2 μm particle columns might have over maximally performing 2.5 μm particle columns is very small. Sub-2 μm particle columns can only yield a gain in separation speed in the range of high-speed/low-resolution-separations (total time based on k = 10 below 5 or 10 min). And even in this range, the actual gain that can be expected is only marginally small (only a few %). The present study hence suggests that the development and the use of particles in the 2–3 μm range should deserve more attention than it did in the past few years. However, to be competitive, this 2–3 μm material should be packed in relatively long columns, with a packing quality matching that of the current best performing 3.5 μm particle columns. The supra-2 μm particles should also be able to withstand the same pressures as the sub-2 μm particle material one is comparing it to.