Gel permeation chromatography is a technique used to find out the relative molecular weight of polymer samples, and to determine the molecular weight distribution of a sample. Essentially, the gel permeation chromagraph will measure the molecular volume and shape function based on their intrinsic viscosity. The machines can be highly accurate thanks to the narrow bands they provide. In addition, they are able to provide results quickly, often in about an hour. Labs that need to determine an estimate for molecular weights find that these machines and this technique can help to speed up their process substantially.
 

While there are a number of models on the market, they have many of the same features and work in a similar fashion. First, there is the gel. The gel is part of the stationary phase, and the user needs to control the gel’s pore size to get accurate results. The eluent, during the mobile phase, is the solvent. Choosing a good eluent is important. It should be a good solvent for polymer, while allowing high detector response. There are two types of pump available – peristaltic and piston pumps.

In addition, there are detectors used with the GPC. A number of different types of detectors are used, but they will typically fall into two different types. Concentration sensitive detectors include infrared absorption, density detectors, refractive index detectors, UV absorption, and differential refractometers. The molecular weight sensitive detectors include multi angle light scattering and low angle light scattering.

Because there are so many different options, you need to understand your specific application to determine which of the machines is the best option to rent. You also need to make sure you consider the size of the GPC to be sure it will work well for the space you have available in the lab. Ease of use may also be a factor. These are machines best left to the use of those who are skilled in their operation or who have at least used them a few times in the past.
 

Some of the companies making these machines include Retificio Ribola, Sartec Group, LabTech Inc., Gilson, Inc., J2 Scientific LLC, Milanese, and Parker Balston Analytical Gas Systems.