Size-exclusion chromatography

Size-exclusion chromatography separates molecules by how readily they enter pores in a stationary phase. Larger molecules access fewer pores and usually elute before smaller molecules.

Pore size: Pore size is the diameter or width of openings in a porous material. The stationary phase’s pore-size distribution determines which molecules can enter its pores.
Chromatography: Chromatography separates mixture components through differential movement between a mobile phase and a stationary phase. Size-exclusion chromatography is one mode of this broader separation method.
Protein purification: Protein purification is the separation of a target protein from other components of a biological sample. Size-based fractionation can separate proteins from aggregates, contaminants, or one another.
Ion-exchange chromatography: Ion-exchange chromatography separates molecules according to their charge interactions with an oppositely charged stationary phase. Unlike size exclusion, it retains molecules through electrostatic attraction rather than pore access.
Void volume: Void volume is the mobile-phase volume outside the pores accessible to a solute. Molecules too large to enter the pores elute near this volume.
Stationary phase: The stationary phase is the material that remains fixed while a mobile phase carries sample components through it. Its porous particles provide the size-dependent pathways that produce separation.
Polymer characterization: Polymer characterization determines properties such as molecular mass, architecture, and size distribution. Size-exclusion chromatography estimates polymer molar-mass distributions when calibrated appropriately.
Affinity chromatography: Affinity chromatography separates molecules through selective binding to a ligand attached to a stationary phase. Its selectivity comes from specific binding, not differences in molecular size.
Total permeation volume: Total permeation volume is the elution volume of a small solute that accesses nearly all stationary-phase pores. It marks the late-elution limit for molecules fully included in the pore network.
Mobile phase: The mobile phase is the liquid or gas that transports sample components through a chromatographic system. Its composition and flow carry molecules through the column without ideally changing their size.

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