Selection of Aqueous SEC (GFC) Columns

For analyzing substances using aqueous SEC (GFC) mode, there are two kinds of columns: silica-based columns and polymer-based columns.

Generally, silica gel provides better resolution because the pore size distribution is sharper and the pore volume is larger than polymer-based columns. However, as silica gel with large pore size cannot be used for GFC analysis because of it brittleness, polymer-based column is suitable for the separation of macromolecules.
In general, silica-based columns are recommended for protein separations of low molecular weight from a few thousand to approximately one million. And polymer-based columns would be best used for the analysis of proteins, lipoproteins or DNA with molecular weights of more than one million. OHpak SB-800 HQ series and SB400-4E series packed with polyhydroxymethacrylate gel allow the analysis of proteins of low molecular weight range of less than 10,000, for which silica-based columns would show low resolution.

Silica-based columns cannot be used with the eluent whose pH is 7.5 or more because silica gel is dissolved in such eluent. In contrast, polymer-based columns have a wider usable eluent pH range and these columns can be washed with alkaline solution, resulting in longer column life. The usable pH range for OHpak SB-800 HQ series is from 3 to 10, whereas the usable pH range for Asahipak GF-HQ series is form 2 to 9.

The packing material of Asahipak GF-HQ or GS-HQ series is a highly cross-linked polyvinyl alcohol gel. Their packing material delays the elution of substances such as human and bovine serum albumins which show strong affinity with the molecular structure of the packing material due to interaction with the molecular structure of the packing material. Making use of this characteristics, Asahipak GS-520 HQ is especially used for the analysis of serum albumin.