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

To contribute to the current debate about the “ideal” particle size range (sub-2μm vs. supra-2μm), the present study compares the kinetic performance of some commercially available sub-2μm and 3.5μm 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 400bar), 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-2μm particle columns might have over maximally performing 2.5μm particle columns is very small. Sub-2μm 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 10min). 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 2–3μm range should deserve more attention than it did in the past few years. However, to be competitive, this 2–3μm material should be packed in relatively long columns, with a packing quality matching that of the current best performing 3.5μm particle columns. The supra-2μm particles should also be able to withstand the same pressures as the sub-2μm particle material one is comparing it to.