Gel exclusion chromatography is a type of
column chromatography. This
lab technique is used to separate the
components of a
mixture by
molecular size and to collect the
molecules which are larger than a certain size. It is similar to
gel filtration; small molecules are slowed or trapped by the
pores in the
gel beads filling the
column, while large molecules, too large to fit into the pores, slide past the beads and get to the bottom of the column first. At this point, the large molecules are collected.
"Gel exclusion" refers to the maximum size of molecule which will fit into the gel bead pores, and this lab technique is used to collect the molecules in the mixture which are larger than, or "excluded" from, the pores.
Some or all of the information in this writeup was taken from the science dictionary at http://biotech.icmb.utexas.edu/; I oversaw the development of the dictionary (the website was mothballed in 1998) and believe I wrote the entry this writeup is partly or wholly based upon.