Cation Exchange Resins

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Purification with cation exchange resins

Cation exchange (CEX) chromatography is a form of ion exchange (IEX) chromatography in which a positively charged biomolecule binds to a negatively charged resin. POROS cation exchange resins can be applied in both capture and polishing steps to purify antibodies, proteins, enzymes, and other biomolecules. Their rigid particle design supports high dynamic binding capacity, even under challenging pH and conductivity conditions. These resins have been implemented in processes from small-scale development to commercial manufacturing.

Benefits of cation exchange resins

Using stable negatively charged ligands, CEX resins assist with efficient purification of proteins and other biomolecules over a wide range of process conditions. Featuring a tightly controlled pore architecture designed for biologics, POROS cation exchange resins offer:

  • High-resolution separations
  • Robust high binding capacity
  • Consistent performance at high flow rates
Binding capacity of POROS XS vs salt concentration and pH capacity at 5% breakthrough

Figure 1. Binding capacity of POROS XS resin with IgG at 5% breakthrough. High binding capacity is obtained under a wide range of process conditions. Column: 0.46 cm (D) x 20 cm (L); buffer: 20 mM MES; load: 5 mg/mL IgG; flow rate: 300 cm/hr.

Chromatogram showing high resolution properties of POROS XS and HS

Figure 2. POROS XS and HS resins present with similar, high-resolution properties. Column: 1 cm (D) x 20 cm (L); buffer A: 20 mM MES, 25 mM NaCl pH 6.2, buffer B: 20 mM MES, 1 M NaCl pH 6.2; elution: gradient 10%–50% buffer B, 7.5 CV; flow rate: 300 cm/hr; protein mix: chymotrypsinogen A, cytochrome C, and lysozyme.

Interested in anion exchange resins?

Applications for cation exchange resins

POROS resins offer an easy, flexible solution for cation exchange chromatography in bind/elute or flow-through modes of operation.

 

POROS cation exchange applications

Bind/elute application

Flow-through application

Polishing of many biomolecules, such as:

  • Monoclonal antibodies (mAbs)
  • VLPs/viruses
  • Fusion proteins
  • High pH recombinant proteins

Polishing by binding impurities under normal bind/elute conditions:

  • Aggregates
  • HCP
  • DNA
  • Viruses

Explore cation exchange resins

Our POROS cation exchange media portfolio includes both strong and weak acid chemistries, each with its specific operating range.
 

Cation exchange resin properties

Resin

Type of CEX resin

Surface chemistry

IgG binding capacity (mg/mL)

pH range

Pore size (Angstrom)

POROS XS

Strong

Sulfopropyl

120

1–14

1,100

POROS HS

Strong

Sulfopropyl

70

1–14

1,020

Ordering information

Explore more chromatography resins

Thermo Fisher Scientific offers POROS ion-exchange, hydrophobic interaction, and mixed-mode chromatography resins for large-scale bioseparations, along with MabCaptureC and CaptureSelect affinity resins designed for efficient purification of mAbs, advanced antibody variants, recombinant proteins, mRNA, viruses, and other biologics.
 

Not sure which resin is right for you?

The Bioprocess Resin Selection Guide is an interactive guide that helps scientists evaluate chromatography resins based on molecule type, application, and scale. Identify products that meet your purification goals and process needs by filtering data on resin chemistry, capacity, and operating conditions.
 

Frequently asked questions

Cation exchange resins can be applied in capture steps where positively charged proteins and other biomolecules bind to negatively charged groups on the resin surface. This approach facilitiates the efficient recovery of molecules, such as therapeutic proteins and enzymes, during the initial purification process. 

These resins are commonly used in polishing steps to reduce impurities that remain after earlier purification. This is standard practice in traditional monoclonal antibody purification platforms. By fine-tuning conditions such as pH and conductivity, researchers can separate closely related variants and improve overall product quality.

Chromatography resources

Access application notes, protocols, and videos that support resin evaluation and process development. Topics include resin selection, column operation, method transfer, and troubleshooting for antibodies, viral vectors, and mRNA. These materials offer guidance for downstream workflows, spanning from early research to manufacturing.
 

Start your purification journey

Use of the products may vary. For specific use statements, please see product literature.