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SEC Column Considerations for Oligonucleotides (15–25 kDa)

Record: 669

Category: Column Selection
Product: KW-802.5, GF-310, GS-320
Sample: Oligonucleotides 

Question

A customer is analyzing oligonucleotides (not oligosaccharides) with an approximate molecular-weight range of 15,000–25,000 Da. Do you have a Shodex column recommendation?

Answer

For oligonucleotides in the 15–25 kDa molecular-weight range, Shodex does not currently have a published application demonstrating high-resolution SEC separation of long oligonucleotides. As a result, column selection depends strongly on the analytical objective (e.g., size screening, aggregate detection, desalting, or use as an orthogonal step prior to RP analysis), and method development is required.

Several Shodex aqueous SEC columns may be evaluated for this molecular-weight range:

  • OHpak KW-802.5 is an aqueous SEC column with a pore size appropriate for lower-molecular-weight macromolecules and may be considered when the goal is group separation or confirmation of molecular-weight distribution rather than detailed length profiling.

  • Asahipak GF-310 is a polymer-based aqueous SEC column designed for biomolecules and provides pure size-exclusion behavior. GF-310 is suitable for evaluating oligonucleotides in this molecular-weight range when the objective is aggregate assessment, MW distribution, or cleanup prior to another chromatographic mode.

  • Asahipak GS-320 operates primarily in SEC mode but can exhibit additional reversed-phase, HILIC, or ion-exchange interactions depending on the mobile phase. GS-320 may be considered when pure SEC does not provide sufficient selectivity, such as in desalting or buffer-exchange workflows for nucleic acids.

Because oligonucleotide retention is influenced by strand type (ss vs ds), charge density, buffer composition, and salt concentration, performance cannot be predicted without experimental evaluation. No column listed above should be assumed to provide base-by-base or n-mer resolution in this size range.

For more tailored recommendations, including guidance on buffer composition, flow rate, detector compatibility, and the intended role of SEC in the workflow, please contact Shodex Technical Support at support@shodexhplc.com.

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