Isocratic separations on thin glycidyl methacrylate-ethylenedimethacrylatemonoliths

In this work, the isocratic separation of oligonucleotides in the ion-excha nge mode on thin glycidylmethacrylate-ethylenedimethacrylate (GMA-EDMA) mon oliths in the form of commercially available CIM (Convective interaction Me dia) 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 comp onents retained on the monolith is proportional to the retention time, whic h 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 hei ght equivalent to a theoretical plate of GMA-EDMA monoliths is calculated t o be 18.0 mu m The capacity factor k' depends, exponentially, on the salt c oncentration. The Z factor calculated from fitted equations increases linea rly with the oligonucleotide's length. It was also found that the differenc e 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 s imilarities between the isocratic separations on conventional columns and o n 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.