Novel stationary phases in high-performance liquid chromatography have been developed continuously. During the recent years, new porous sub-2-micron packing materials, core-shell materials, monolith columns have been introduced to speed up separations keeping the efficiency high.

The novel phases guarantee fast mass transfer kinetics due to the shorter diffusion paths.

Pore sizes below 100 Å provide good efficiency for the separation of small molecules, but in bioseparations pores sizes larger than 300 Å are required. Besides pore size itself, the pore size distribution is another factor that influences the separation efficiency. 

On the other hand, the developments of column technology, the smaller particles that require larger pressure, bring along novel problems. The frictional heat limits the further increase of efficiency when sub-2-micron particles are employed.

The study of the mass transfer properties and thermodynamics of retention on modern fully porous and core-shell packing materials reveals the separation power of the latest generation of stationary phases. Concepts and results are presented focusing on the tools of stationary phase characterization.