Size-exclusion chromatography

Size exclusion chromatography (SEC) is an analytical technique used to analyze the size distribution of molecules in a sample. SEC separates molecules according to their size in a column filled with fine porous beads.

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What is size-exclusion chromatography and how does it work?

Size exclusion chromatography (SEC), also known as gel permeation chromatography (GPC), is an analytical technique that separates molecules based on their size. It is used to analyze the size distribution of the molecules in the sample. With calibration standards, SEC can be used to characterize molecular weights of unknown molecules. SEC can be used to measure polymers from a few hundred to several million Daltons.

The sample is dissolved in a solvent and dissolved molecules are separated by their particle size in a column filled with porous beads containing specific pore size distribution. Since the small molecules diffuse into the pores, the flow of molecules through the column slows down as particle size decreases. Large molecules do not fit in the pores and elute in the void space of the column. Therefore, smaller dissolved molecules flow more slowly through the column than larger molecules allowing the size distribution to be recorded.

Need an analysis?

Measurlabs offers SEC analyses for the molecular weight distribution analysis of lignin. The analysis can be ordered directly through our website, and our experts will check the suitability of the measurement for your samples before processing the order. For samples consisting of large macromolecules, we also offer SEC-MALS analyses.

Feel free to contact us at any point, if you have questions relating to our services, or if you wish to request a quote. You can reach us at or through the form below.

Suitable sample matrices

  • Polymers
  • Proteins
  • Macro molecules

Ideal uses of SEC analysis

  • Molecule size distribution characterization
  • Analysis of average molecular weights

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  • Do you have a recurring need for these tests? If yes, how often and for how many samples at a time?

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Frequently asked questions

What is SEC commonly used for?

SEC is used to characterize the size distribution of macromolecules.

One common application is the testing of lignin to determine its molecular weight distribution, which varies based on the type of biomass lignin is extracted from.

What are the limitations of SEC?

If the molecules have close molecular weight, it may be difficult to distinguish them leading to uncertainty in the analysis.

What kind of samples can be analyzed with SEC?

Solid macromolecule samples that can be dissolved.

Macromolecule-containing solutions.

What is Measurlabs?

Measurlabs offers a variety of laboratory analyses for product developers and quality managers. We perform some of the analyses in our own lab, but mostly we outsource them to carefully selected partner laboratories. This way we can send each sample to the lab that is best suited for the purpose, and offer high-quality analyses with more than a thousand different methods to our clients.

How does the service work?

When you contact us through our contact form or by email, one of our specialists will take ownership of your case and answer your query. You get an offer with all the necessary details about the analysis, and can send your samples to the indicated address. We will then take care of sending your samples to the correct laboratories and write a clear report on the results for you.

How do I send my samples?

Samples are usually delivered to our laboratory via courier. Contact us for further details before sending samples.