Isocratic separations on thin glycidyl methacrylate-ethylenedimethacrylate monoliths

In this work, the isocratic separation of oligonucleotides in the ion-exchange mode on thin glycidylmethacrylate-ethylenedimethacrylate (GMA-EDMA) monoliths in the form of commercially available CIM (Convective interaction Media) disks is presented. It was found that isocratic separation occurs even on monoliths with a thickness of only 0.75 mm, Peak broadening of the components retained on the monolith is proportional to the retention time, which in turn is proportional to the thickness of the monolith. Peak height is inversely proportional to the retention time. From these results it can be concluded that the mechanism of the separation on such monoliths is similar to that in HPLC columns filled with conventional porous particles, The height equivalent to a theoretical plate of GMA-EDMA monoliths is calculated to be 18.0 mu m The capacity factor k' depends, exponentially, on the salt concentration. The Z factor calculated from fitted equations increases linearly with the oligonucleotide's length. It was also found that the difference between peak retention volume slightly increases with the flow-rate when the experiments are performed in the range from 0.5 to 7 ml/min. From the similarities between the isocratic separations on conventional columns and on thin GMA-EDMA monoliths it is reasonable to believe that separation based on a multiple adsorption/desorption process also occurs in thin monoliths. (C) 1999 Elsevier Science B.V. All rights reserved.