Gel Permeation Chromatography (GPC) is a powerful technique that provides a direct measurement of molecular weight, a critical property in characterizing natural and synthetic polymers. There is no universal GPC system with the capability to separate every polymer-based exclusively on size, so how do you choose the correct column tailored specifically for your sample?

Choosing a Mobile Phase

It all starts with the mobile phase. What is your sample polymer soluble in? A polymer that is insoluble cannot be analyzed by GPC, making solvent selection paramount. For an efficient GPC separation based only on size, the optimal solvent should be strong enough to minimize the sample-column interaction.


Don’t Sacrifice on Resolution

When choosing GPC columns, it is essential to decide on the level of resolution desired for your samples and standards. Remember the golden rule: resolution and separation efficiency increases directly with the column’s volume (pore volume). The length and internal diameter (ID) of each column should be carefully considered prior to purchasing any column set. We would suggest:

  1. Using a longer column, or multiple columns in series (two 30 cm in series vs. one 30 cm column)¹
  2. Choosing a column with a larger internal diameter (22 mm vs. 7.8 mm)

An advantageous solution to poor resolution is to include an additional column in series to your current system. “Free resolution” can be obtained by increasing the column temperature or by choosing the optimal injection volume/concentration for your system.


Pore Size Matters

GPC utilizes a non-interactive stationary phase, composed of a porous network, allowing for an elution order based on decreasing molecular size.  There are a number of pore sizes available, and each pore size excels at separating a specific molecular weight range (Table 1).The Mixed Bed column is a linear column, and is strongly recommended for routine or unknown sample analyses. The column pore size should be chosen based on the suspected molecular weight range of the polymer being analyzed.


“It’s Just a Phase…”

Let’s summarize what we know now:

  • the chromatographic eluent based on sample solubility,
  • the number of columns and dimensions based on resolution desired,
  • and the pore size based on the suspected MW range of the sample

Would you like to learn more? Contact a member of the RQM+ Lab Services team today with any questions about gel permeation chromatography, or selecting a GPC column.

¹This would result in a 2 fold increase in pore volume, based on an increase in column length.


Related Techniques

We are passionate about your success. Tell us more about your regulatory and quality needs to learn about how we can help.

Book a Consultation


To display custom copy instead of global copy in this section, please go to Show Global Content for Bottom CTA? toggle in the "Contents" tab to the left, toggle it off, save, and then REFRESH the page editor, the custom text will then show up and ready to be edited.

Turning the global content back on will be the same process, go to the toggle and toggle it back on, save and refresh!