Gel Filtration Chromatography

• ENrich™ Size Exclusion
  Chromatography Columns

  

  Need high-resolution separations at high flow rates? Use ENrich size exclusion chromatography columns.

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• Bio-Spin^® and Micro
  Bio-Spin™ Size Exclusion Columns

  

  Use the convenient, ready-to-use Bio-Spin and Micro Bio-Spin size exclusion columns for rapid, effective, and economical cleanup of DNA, RNA, and protein samples.

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• Econo-Pac^® 10DG Desalting
  Prepacked Gravity Flow Columns

  

  Use Econo-Pac 10DG prepacked gravity flow gel filtration chromatography columns for easy and fast desalting.

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• Gel Filtration
  Chromatography Media

  

  Select gel filtration media in a variety of bead and mesh sizes for desalting, buffer exchange, and size fractionation in aqueous or organic solutions.

  Buy Gel Filtration Resin

Gel Filtration Chromatography Mechanism

In a gel filtration chromatography column, the stationary phase is composed of a porous matrix, and the mobile phase is the buffer that flows in between the matrix beads. The beads have a defined pore size range, known as the fractionation range. Molecules and complexes that are too large to enter the pores stay in the mobile phase and move through the column with the flow of the buffer. Smaller molecules and complexes that are able to move into the pores enter the stationary phase and move through the gel filtration column by a longer path through pores of the beads.

Any molecule or complex that is above the fractionation range for a particular gel filtration chromatography column will move through the column faster than any molecule that can enter the stationary phase. Therefore, any constituent in the sample that is above the fractionation range will elute first (in the void volume) before anything that is in the fractionation range. The minimum size that will remain in the mobile phase and not enter the stationary phase is known as the exclusion limit. Bio-Rad offers gel filtration chromatography media and columns with exclusion limits ranging over three orders of magnitude, from 100 daltons to 100,000 daltons (100 kDa).

Molecules and complexes that can enter the stationary phase will be fractionated according to their sizes. Smaller molecules will migrate deep into the pores and will be retarded more than larger molecules that do not so easily enter the pores, and are thus eluted from the column more quickly. This difference in pore migration leads to fractionation of components by size with the largest eluting first.

In gel filtration chromatography columns designed for desalting, buffer exchange, and the removal of small molecules such as nucleotides, the salts and small compounds readily enter the pores, are retarded, and migrate more slowly through the column than the larger proteins or nucleic acids. Therefore, the components of interest in the sample are eluted in advance of salts, nucleotides, etc. DNA cleanup kits using this mechanism often contain gel filtration spin columns.

Resolution, here defined as the sharpness of the boundaries between size fractions, is determined by bead size and a number of other factors. Smaller bead size generally yields higher resolution in a gel filtration chromatography column. Compact molecules diffuse through the stationary phase faster than linear molecules. Size exclusion, fractionation range, and elution rate are affected by buffer composition, ionic strength, and pH. For the fractionation of complex mixtures of proteins, elution times and size exclusion limits may need to be determined empirically.