overlap concentration and a naive question
Posted: Tue Jun 30, 2009 7:28 pm
If the injected polysaccharide solution concentration is higher than the overlap concentration (1/intrinsic viscosity), then dilution of the sample will take a relatively (many minutes, maybe hours) long time. This is because the chains need to disentangle themselves. These kinetic effects will vary from system to system due to differing volumes from the injector to the column.
Try preparing a very low concentration sample for both systems. If you cannot get a good concentration signal for such a low concentration sample, use your MALS signals to compare the results.
OK, now for the naive question. Did you make up some easy sample (maybe about 100k dextran) and check system reproducibility for the second system? It's a time consuming test, but will identify whether your issue is with this sample or with the system.
Try preparing a very low concentration sample for both systems. If you cannot get a good concentration signal for such a low concentration sample, use your MALS signals to compare the results.
OK, now for the naive question. Did you make up some easy sample (maybe about 100k dextran) and check system reproducibility for the second system? It's a time consuming test, but will identify whether your issue is with this sample or with the system.