Question: What is GPC?

Joseph Cook answered on 13 Jun 2010:

GPC stands for ‘Gel Permeation Chromatography’. It’s used to look at the sizes of polymers, which are long chain molecules. They are used in many things, but you’d come across them a lot in every day life as plastics. When you have a polymer, there is always a range of sizes in the sample. It’s often important to know what the range of sizes is, whether it is a narrow or a wide range.

When you do GPC, much of the process is run by a computer, but the idea is that you dissolve your polymer in something (like water, for example) and then pump it through a column with a porous substance in it. The polymer molecules can become trapped in the pores and the length of time they stay in the pores depends on their size, so they come out of the end of the column at different times. The smallest molecules fit into the smallest pores and so get trapped for a long time, whereas the largest molecules are too big to fit into any pores and don’t get trapped at all, so they flow through quickly.

You can make a graph of the amount of polymer that comes out of the end of the column after different periods of time, and this tells you the distribution of sizes in your sample.

I hope this is clear!