Page "Gel permeation chromatography" Paragraph 2

GPC separates based on the size or hydrodynamic volume ( radius of gyration ) of the analytes.

This differs from other separation techniques which depend upon chemical or physical interactions to separate analytes.

Separation occurs via the use of porous beads packed in a column ( see stationary phase ( chemistry )).

Schematic of pore vs. analyte sizeThe smaller analytes can enter the pores more easily and therefore spend more time in these pores, increasing their retention time.

Conversely, larger analytes spend little if any time in the pores and are eluted quickly.

All columns have a range of molecular weights that can be separated. Range of molecular weights that can be separated for each packing material If an analyte is either too large or too small it will be either not retained or completely retained respectively.

Analytes that are not retained are eluted with the free volume outside of the particles ( V < sub > o </ sub >), while analytes that are completely retained are eluted with volume of solvent held in the pores ( V < sub > i </ sub >).

The total volume can be considered by the following equation, where V < sub > g </ sub > is the volume of the polymer gel and V < sub > t </ sub > is the total volume: