Equivalency Considerations Between ZORBAX GF-250 and Shodex KW Series SEC Columns

Record: 620

Category: Column Selection
Product: KW-803
Sample: Proteins

Question

I would like to verify an equivalency recommendation.

The Agilent ZORBAX GF-250 column has a 150 Å pore size, yet Agilent literature describes it as suitable for size exclusion chromatography (SEC) of proteins.
Is this based on average protein size, and how should this be interpreted when selecting a Shodex equivalent?

Answer

When comparing SEC columns across manufacturers, it is important to note that pore size alone does not define the effective molecular weight separation range, especially for proteins, whose elution behavior depends on hydrodynamic volume rather than nominal molecular weight.

Although ZORBAX GF-250 has a reported pore size of 150 Å, it is still capable of SEC separations for proteins across a broad range because proteins are compact, globular molecules. As a result, they can access pores differently than linear polymer standards, allowing SEC behavior even on columns with relatively small nominal pore sizes.

Agilent reports an effective molecular weight range of approximately 4 kDa to 400 kDa for ZORBAX GF-250 under protein SEC conditions.

When selecting a Shodex equivalent, the target molecular weight range of the sample is the most important factor.

• KW-802.5 / KW402.5
  • Effective protein MW range: up to ~150 kDa
  • Suitable for lower-MW proteins and fragments
• KW-803 / KW403
  • Suitable for higher-MW proteins, extending beyond 150 kDa
  • Higher lower-MW limit compared to 802.5 series (lower end ~8 kDa)

If the customer’s proteins extend toward the upper end of the ZORBAX GF-250 range, KW-803 or KW403 would be the more appropriate choice.

Additional Comments

• pH range
  • ZORBAX GF-250: typically pH 3–8
  • Shodex KW series: approximately pH 3–7.5
    While similar, this difference should be confirmed if the method operates near pH 8.
• Target MW confirmation
  Customers should confirm both the upper and lower molecular weight limits of their samples to ensure appropriate pore size selection and avoid loss of resolution at either end of the range.

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