Gel Permeation Chromatography (GPC)
What is Gel Permeation Chromatography?
Gel permeation chromatography (GPC) is a type of size exclusion chromatography (SEC) that uses to separate analytes on the basis of their size when dissolved in organic solvents. The technique is mainly used to separate polymers on the basis of size or hydrodynamic volume. The separation can be done by the use of porous beads packed in a column.
The smaller analytes may enter the pores more easily. They spend more time in these pores and increasing their retention time. Therefore, these molecules will elute last.
Conversely, larger analytes spend little time and are eluted more quickly. Therefore, these molecules will elute fast. All chromatography columns have a range of molecular weights that can be separated by gel permeation chromatography (GPC) techniques.
Gel Permeation Chromatography Instrumentation
One of the most important components of the gel permeation chromatography instrument is the GPC column. The experimental design of the GPC instrument is similar to that of other chromatography instruments. The main component in gel permeation chromatography instrumentation may include,
- Gels
- Column
- Eluent
- Pump
- Detector
Gels in GPC technique
Gels are a stationary phase for GPC instrumentation. The gels used in GPC separation are mostly made from hydrophilic gels of dextran, agarose, or polyacrylamide. The pore size of a gel must be carefully controlled for the separation of a given analyte.
Column
The column used in gel permeation chromatography is filled with microporous packing material. The selecting column for your requirements depends on particle size, pore size distribution, temperature, solvent compatibility, resolution, molecular weight range, etc. The most commonly used columns for GPC separation are,
- Styragel Columns: used in organic polymer analysis
- Ultrahydrogel Columns: used in aqueous polymer analysis
- HSPgel Columns: used for high-speed organic materials analysis
- HSPgel AQ Columns: used for high-speed aqueous polymer characterization
- Ultrastyragel Preparative Columns: used for organic polymer isolation
- Envirogel Columns: used for high-resolution GPC Cleanup
- Shodex Columns: used for organic polymer characterization
Eluent
The eluent or mobile phase in the GPC technique should be a good solvent for the polymer or analyzed substances. The most common eluents for polymers that used GPC analysis or separation are tetrahydrofuran (THF), o-dichlorobenzene and trichlorobenzene, crystalline polyalkenes and m-cresol and o-chlorophenol, and crystalline condensation polymers.
Pump
Generally, two types of pumps such as piston or peristaltic pumps are available or used in GPC analysis or separation.
Detector
A doctor in the GPC technique may use to monitor the concentration by weight of the polymer in the eluting solvent. There are many types of detectors available in the market for GPC analysis. They may be divided into two main categories,
- Concentration sensitive detectors: UV absorption detectors, differential refractometer (DRI) or refractive index (RI) detectors, infrared (IR) absorption, and density detectors.
- Molecular weight sensitive detectors: low-angle light scattering detectors (LALLS) and multi-angle light scattering (MALLS).
Application of Gel Permeation Chromatography
- Fractionation of molecules and complexes in a predetermined size range can be done by SEC techniques
- The gel permeation chromatography technique is useful for separating and purifying proteins, polysaccharides, enzymes, and synthetic polymers.
- It may be used to determine the quaternary structure of protein molecules.
- It is used for the separation of sugar, large proteins, peptides, rubbers, and other materials based on their size.
- Gel permeation chromatography is an ideal process for separating organic and biopolymer molecules.
