Gel Permeation Chromatography- Definition, Principle, Parts, Steps, Uses


Gel permeation chromatography (GPC) is a type of size-exclusion chromatography (SEC) that separates molecules based on their size, typically in organic solvents. The technique is often used for the analysis of polymers, such as plastics, rubbers, proteins and polysaccharides.

GPC can provide information about the molecular weight distribution, average molecular weight and molecular structure of polymers. These properties are important for determining the physical, chemical and mechanical properties of polymer materials.

The principle of GPC is that molecules of different sizes pass through a column packed with porous beads at different rates. Larger molecules cannot enter the pores and elute faster than smaller molecules that can penetrate the pores partially or completely. The elution time of each molecule is related to its size and can be calibrated using standards of known molecular weight.

GPC can be performed in a wide range of solvents, depending on the solubility and stability of the polymer sample. The most common solvents are tetrahydrofuran (THF), chloroform, dimethylformamide (DMF) and water. The choice of solvent affects the swelling and shrinking of the porous beads and the interaction between the polymer and the stationary phase.

GPC requires specialized instrumentation and components, such as columns, pumps, detectors and software. The columns are filled with gel-like materials that have well-defined pore sizes and are chemically inert and mechanically stable. The pumps deliver a constant flow rate of solvent and sample through the column. The detectors measure the concentration or other properties of the eluting molecules, such as refractive index, ultraviolet absorbance, light scattering or viscosity. The software controls the operation of the system and analyzes the data to calculate the molecular weight parameters.

GPC is a simple, fast and reliable technique that can be used for various applications, such as:

  • Protein fractionation and purification
  • Molecular weight determination of natural and synthetic polymers
  • Characterization of polymer branching, cross-linking and end-groups
  • Quality control of polymer products
  • Investigation of polymer degradation and aging
  • Separation of polymer additives, such as antioxidants, stabilizers and plasticizers

In this article, we will discuss the principle, components, steps, uses, advantages and limitations of GPC in more detail.