SILICA-GEL AND CARBON COLUMN PACKINGS FOR USE IN HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

The basic properties of the most important groups of HPLC column packings are briefly compared. The physical properties of totally porous silica and carbon-based sorbents, especially the pecularities of their pore structure, are discussed in more detail. The advantages of the sponge-like sorbent structure over a corpuscular structure are elucidated. The unconventional concept of pellicular sorbents with a thick porous layer and, especially, the concept of superficially crazed sorbents is presented. Besides pores of the sizes that are necessary for the particular application in HPLC, the latter material also contains large and relatively deep cracks with widths two to five times larger than the specific mean pore diameters. An experimental crazed silica gel is presented and some of its chromatographic properties are shown.