Physical characterization and evaluation of HPLC columns packed with superficially porous particles.

Two HPLC columns packed with superficially porous packing material (Kinetex™ 1.7 and 2.6 µm C18 particles) were evaluated in terms of their physical properties and performance characteristics. These columns were compared to a column packed with a sub-2 µm totally porous material and to a Halo(TM) column packed with 2.7 µm C18 superficially porous packing. The columns packed with superficially porous particles displayed a comparably narrower size distribution, which is narrower than the distribution of the totally porous sub-2 µm particles. Physical characteristics of the Kinetex™ particles were evaluated in terms of surface area, pore diameter, and specific pore volume. Total, external, internal, and shell porosities among the four different columns were evaluated and compared. The specific permeability for the Kinetex™ columns showed values close to those predicted by the Kozeny-Carman equation. All four columns were evaluated in terms of their chromatographic performance and compared using the Knox equation. The columns packed with the 2.6 and 2.7 µm superficially porous materials showed reduced plate heights below 2, whereas the sub-2 µm particles showed values of 2.2 and above.