= Size-exclusion chromatography
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= SEC
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= Gel filtration
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= Gel permeation chromatography
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<Size-exclusion chromatography> separates dissolved <molecules> by their <hydrodynamic size> in the chosen <solvent>. A larger species that cannot enter the packing's pores travels with the liquid between particles and elutes earlier. Smaller species explore more internal liquid and elute later. The column is not a sieve that permanently traps the large species: exclusion makes them leave first. “<Gel filtration>” is common for aqueous separations; “<gel permeation chromatography>” is common for organic-solvent analysis of <polymers>. <SEC molar mass calibration> translates size-dependent elution into a standard-relative estimate of <molar mass>, rather than a universal absolute measurement.
This makes <SEC> useful for separating <proteins> from small dissolved species, comparing <protein aggregation>, and characterizing dissolved <polymer> chains. The <residual-group monitoring of polyurethane formation> experiment already illustrates <polymer> calibration: its reported <molar masses> are relative to <polystyrene> standards. <Size-exclusion characterization of chain polymers> explains why an elution trace alone cannot count chains or establish their growth mechanism.
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