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About Gel Permeation Chromatography

Gel Permeation Chromatography (GPC), also known as Size Exclusion Chromatography (SEC), separates polymer molecules based on their size. GPC is used to measure the molecular weight distribution of polymer samples. Absolute  molecular weight measurements are performed using multi-angle light scattering (MALS) detection. GPC-MALS molecular weight measurements provide the absolute, or true, molecular weight of a sample without reference to polymer calibration standards. Molecular weight measurements can also be performed using GPC with conventional column calibration, in which molecular weights are calculated relative to a series of polymer standards.

  • Approaches

    There are many analytical uses for GPC Analysis.  Some of the most common ways we use GPC/SEC to meet our clients needs include: 
    • The analysis of polymer materials to determine molecular weight distributions
    • Measurement of absolute molecular weights using light scattering
    • Analysis of molecular size and polymer chain conformation in solution using a differential viscometer detector
    • Relative molecular weight measurements using refractive index or UV/vis absorbance detector
    • Molecular weight analysis of polymers in organic solvents
    • Analyzing water soluble polymers in aqueous mobile phases
    • The quantitative analysis of low molecular weight molecules such as antioxidants, light stabilizers, plasticizers, lubricants and spin finishes
    • Preparative SEC with fraction collection for deformulation and contamination analysis.

    We can provide GPC analysis using virtually any solvent system, including hexafluoroisopropanol (HFIP), which is the preferred GPC solvent for polyamides, polyesters, and nylons.  As stated by Jason Todd, one of our Chromatography Experts,  "The use of HFIP as a GPC solvent allows us to provide high quality molecular weight data on commercially important polymers. HFIP is advantageous because it allows the GPC analysis to be performed at room temperature. Other solvents for these plastic materials typically require high temperatures for solubility. Higher temperatures increase the risk of sample degradation during analysis. HFIP also provides higher quality GPC results compared to the high temperature solvents."

  • Instrumentation & Sample Considerations

    Wyatt Technology TREOS and HELEOS II multi-angle light scattering (MALS) detectors for measurement of absolute molecular weight

    Wyatt Technology Optilab T-rEX refractive index detectors for online measurement of polymer concentration and offline dn/dc measurements

    Tosoh EcoSEC HT high temperature GPC system for analysis of polyolefins

    Samples submitted for GPC/SEC testing must be soluable in an organic solvent or in water. The minimum sample size for GPC Analysis is 20 mg.

    Contact us to talk through your specific sample considerations and analysis needs.

  • Experience

    Examples of our experience with SEC Analysis/GPC Analysis include:

    • Size Exclusion Chromatography in Hexafluoroisopropanol for engineering polymers (GPC in HFIP)
    • Determining the change in molecular weight due to processing conditions, sterlization conditions, or after synthesis
    • Failure Analysis Testing
    • Analysis of implantable medical devices
    • Analysis of packaging materials, to include medical packaging materials