3D representation of an anion resin attracting negatively charged molecules

Ion exchange chromatography (IEX) is a purification technique that allows for the separation of molecules based on their surface charge. The process exploits the interaction between negatively or positively charged molecules in a sample and an oppositely charged chromatography matrix.

Ion exchange chromatography serves as the workhorse in downstream processing and plays a significant role in impurity removal. Our large portfolio of anion and cation exchange resins are applied in many commercial and late-stage processes for the manufacturing of:

  • Antibody Therapeutics
  • Vaccines
  • Gene Therapies
  • Biosimilars

A major improvement to the performance of traditional ion exchangers, POROS resins provide an easy solution for ion exchange chromatography in bind/elute or flow through modes of operation.


Bind/Elute application

Flow through application

Cation exchange

Polish of many biomolecules such as:

  • Monoclonal antibodies (mAbs)
  • VLPs
  • Viruses
  • Fusion and recombinant proteins with alkaline pI

Polish for mAbs by binding impurities under normal B/E conditions such as:

  • Viruses
  • HCP
  • Aggregates

Anion exchange



Capture of:

  • Proteins/mAbs
  • Viruses
  • Plasmid DNA

Polish of:

  • Viral vectors—separation of empty particles

Trace impurity removal by binding impurities such as:

  • DNA
  • Viruses
  • HCP
  • Aggregates
  • Endotoxin

Selecting the right resin

Choosing the right ion exchange resin will help to ensure quality, productivity, and effectiveness of the purification process. Biomolecules vary in their net charge depending on the solution pH. Select either an anion exchange or cation exchange resin according the purification step and charged properties of the target molecule.

Isoelectric point (pI)

The point along the pH scale at which the molecule or surface carries a zero-net charge.

  1. When the pH falls below the molecule’s pI, the protein carries a net positive charge and will bind to an anion exchanger.
  2. When the pH falls above the molecule’s pI, the protein carries a net negative charge and will bind to a cation exchanger.
Line graph showing how pH changes affects a proteins binding profile

POROS chromatography resins

POROS resins exhibit high capacity, high resolution, and salt tolerance, built to deliver exceptional separation capability and to meet the increasing demands of process intensification. High performance resins, like POROS, can simplify the development process, balance all the purification requirements, and help develop more efficient and cost-effective downstream processes.

three-panels describing POROS bead features—high capacity, high throughput, and superior resolution

The unique features of the POROS chromatography resins

  • Poly(styrene-divinylbenzene) backbone—resulting in linear and scalable performance. The beads are rigid and have a high mechanical strength enabling easy and reproducible scale-up. The polymer backbone is chemically stable allowing for stringent cleaning when needed.
  • Large throughpores—leading to a reduced mass transfer resistance compared to other resins. Capacity and resolution are maintained over a wide range of linear velocities, thereby establishing a more efficient purification process.
  • 50-micron bead size—providing superior resolution. The smaller particle size results in tighter peaks and smaller elution volumes, helping to overcome volume restrictions in following steps in production.

Related resources

Selecting the optimal resin for your processes

Download the article and learn how efficient purification strategies are critical to overcoming manufacturing limitations. 

Download article

Platform purification approaches for the production of complex biologics

Process development scientists are looking for new tools that will clear even more impurities in a single step while maintaining high recoveries and process flexibility. Watch this video to learn how Thermo Scientific POROS Ion Exchange chromatography resins address purification challenges of today’s biomolecules.

Bioprocessing resources

Access a targeted collection of scientific application notes, case studies, posters, white papers and more for bioprocessing:

Pharmaceutical Grade Reagent. For Manufacturing and Laboratory Use Only.