31 Jan

Monolithic Columns

High Performance Liquid Chromatography is one of the most useful analytical techniques for separation and identification of substances.  Traditional HPLC columns are packed with spheres of modified silica.  The smaller the spheres the greater the surface area of each sphere.  This smaller size means the analyte molecules have more access to pores in the spheres; this aids in separation.  Unfortunately the smaller the sphere the higher the back pressure on the column.  The pressure limit in most chromatography systems is about 5000 psi.  To compensate for the higher back pressure lower flow rates must be used and this leads to longer analysis times.  One of the solutions to this dilemma is the use of monolithic columns.  Monoliths are formed from polymers and fashioned into porous rods with millions of pores.  Monoliths can be organic as in Polystyrene-divinylbenzene (PS-DV) or inorganic as in Silica.  The open structure of the monoliths give the analyte molecule better access to the pores.  This is especially helpful for the separation of macromolecules such as proteins.  The open structure of the monoliths eliminate the back pressure problem.  Merck and Agilent currently manufacture monolithic columns.

Robin Prymula