Comparison of the kinetic performance of different columns for fast liquid chromatography, emphasizing the contributions of column end structure.

The kinetic performance of five chromatographic columns designed for fast liquid chromatography with different column packing materials - including fully porous (2.0 and 1.9μm particles), core-shell (2.6μm particles) or monolithic packings - with identical column dimensions (2.1×50mm) was tested. Since the tested monolithic column showed systematically better efficiency for early eluting compounds than the packed columns, an additional band broadening effect was suspected for the packed columns. The effects of the presence of the frits and the bed heterogeneity of the columns near the frits were characterized by a column-reversal method. It has been shown that significant differences - even 20-25% difference in efficiency - can exist between the two ends of the packed columns, while the monolithic column shows rather similar performance at either column end.