a substrate for retaining a particulate packing medium within a chromatography column is disclosed . the substrate is formed from a polymer material and positionable to retain the packing medium within the column . the polymer has pores sized to retain the packing medium within the column but allow fluid , such as transport liquid or carrier gas to pass through . a method of forming the substrate within the column is also disclosed . the method includes placing a polymer precursor into the column and then polymerizing it to form the substrate .