Size exclusion columns

[randy]

I don't know much about these except they are normally used for analysis of proteins and polymers. Is there a minimum size and/or molecular weight for which these types of columns are useful? I've been asked to research and purchase one of these columns for some of the "out there" stuff that comes into the lab every so often, but we don't normally do proteins or polymers, mostly compounds in the environmental vein.

[Noser222]

Is there a minimum size and/or molecular weight for which these types of columns are useful?

Yes, most suppliers will show a plot of molecular weight vs. retention time for each column. They should also have a guide based on the nature of the samples you are analyzing to minimize unwanted retention effects.

[Rande]

Randy,

I would like to give you advice about SE-HPLC. Could you be more specific about what type of samples you expect to be analyzing.

There are a few different column chemistries available and you need to use the right tool for the job. The first difference is whether you will be using organic solvents or aqueous buffers. Then you need to know the expected molecular weight range.


I would suggest you check out the following vendors :

TOSOH Bioscience
http://www.separations.us.tosohbioscience.com/

GE
http://www4.gelifesciences.com/aptrix/u ... one=Labsep

Phenomenex
http://www.phenomenex.com

Bio-Rad
http://www.bio-rad.com/

Waters
http://www.waters.com/watersdivision/Co ... DRS-5KJKSP

Polymer Standards Service
http://pssgpcshop.com/


In my experience, SE-HPLC is often an art (or black magic) and different samples do not always behave as expected. Different columns and different buffers will often give different results.

Good Luck and Have Fun,

[randy]

The problem is that the application for the column would be as a sort of backup or catch-all for compounds that don't work on other types of columns. For instance, I was working with two diamines a few months ago that didn't separate at all on a C18 or cation mixed-mode column. The compounds did end up separating on a Thermo Hypercarb column, but one of the diamines was still unretained. It was suggested that I try a size exclusion column, but I didn't know enough about them or have the time to try one out and learn.

In any case, the molecular weight of compounds I'd be working with will be well below 1000. I wasn't sure if there was some sort of cutoff for molecular size below which an SEC just wouldn't be suitable.