Gel Permeation Chromatography (GPC) /
Size Exclusion Chromatography (SEC)

Molecular weight separation

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Gel permeation chromatography (GPC) is a liquid chromatography method where separation is based on molecule size (instead of chemical properties). Here, the mobile phase rarely, if ever, changes composition, and instead flows isocratically (i.e., same composition) in order to pull the sample components through the stationary phase. The GPC column (i.e., stationary phase) is filled with many pores of various sizes. Smaller molecules can diffuse more deeply into more pores more often, while larger molecules are less likely to enter pores and do not spend as much time diffusing in and out of pores within the GPC column. These diffusion times lead to large molecules eluting first and small molecules eluting last. Because retention time, and thus molecular weight, is dependent on how much time sample molecules diffuse through the column pores, samples should NOT interact with the column’s stationary phase. GPC is most commonly applied to analyzing the relative molecular weights (Mn, Mw) and dispersity (Đ) of polymeric samples.

Instrument	EcoSEC Elite HLC-8420 GPC system, Tosoh Lens3 MALS-V Light Scattering detector, Tosoh
Stationary phase	HR, Tosoh (standard separation) HR, Tosoh (ultra-high separation)
Mobile phase	Tetrahydrofuran (THF)
Separation range	200 Da – 4 MDa (standard separation) 200 Da – 400 MDa (ultra-high separation) COMING SOON!
Detector(s)	Viscometry UV RID MALS
Compatible molecular materials	organic polymers, oligomers, epoxies, polymer additives, phenolics, unsaturated polyester, urea/formaldehyde, polyethylene glycol, ethanolamines, melamine resin
Calibration	Polystyrene (PS)

The tetrahydrofuran (THF) system is compatible with most organic polymer materials containing phenolic, esters, ethylamines, etc. The system is equipped with several detectors for full characterization of the macromolecule, beyond traditional molecular weight determination. Viscometry analysis allows for (why useful in GPC). Ultra-violet (UV) absorbance provides (why UV useful in GPC). Multi-angle light scattering (MALS) is a light scattering detector (why mals useful in GPC). Additionally, refractive index detection (RID) is still available for conventional GPC detection. The THF GPC system uses polystyrene (Mp = 580 – 298,600 Da) for standard calibration using either MALS calibration or RID conventional calibration.

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The hexafluoroisopropanol (HFIP) system is useful to analyzing solvent-resistant polymers using conventional refractive index detection (RID). The HFIP GPC system uses poly(methyl methacrylate) (Mp = 600 – 520,000 Da) for conventional calibration.