Gel permeation chromatography (GPC) measures the molecular weight distribution of polymers.
There has been a growth of interest in GPC as polymers become more widespread in the pharmaceutical and chemical industries and increasingly, analysts are turning to GPC to characterise materials.
Many analysts come to GPC from a high performance liquid chromatography (HPLC) background and initially find some of the practical requirements surprising, which can lead to a misconception that GPC is adifficult'. In fact, with due consideration of the separation mechanism, GPC is a straightforward technique.
For example, in GPC, typically between two and four columns are employed with lengths of 300mm and diameters of 78mm. This is very different to HPLC, but results from the fact that separation in GPC is performed in the pores of the packing material. More pores mean greater resolution and therefore relatively large column volumes are utilised. Similarly, injection volumes of 20200ml are common, reflecting the need to inject large amounts of material at low concentrations to ensure that viscosity effects do not hamper chromatography.
With knowledge of the separation mechanism involved and its influence on the chromatography, GPC can quickly become an important and useful component in the modern analytical laboratory.
Polymer Laboratories is based in Church Stretton, Shropshire, UK. www.polymerlabs.com
