Chromatography Forum

Hello All,

just a quick question regarding particle size and GPC ( or Size Exclusion)columns. I have a sample that needs to be analysed by GPC. The column in question is 5um particle size and 100A pore size. Now, my concern is that the sample to be run contains 2um particles and and i am unsure of the design of GPC columns, would these particles simply pass around the column particles or is it the case that the column particles are that tightly paked the sample would clog the column up?

any info would be appreciated.

Many Thanks

Steve

The 2µm particles, if rigid and/or globular, will probably get stuck on the frits.

You need to filter out the 2 micron particles before you inject the sample onto a GPC column. The column inlet frit is designed to protect the column, but it is not a filter.

what is the exclusion limit for this small pore volume of GPC? this pore volume looks very similar to normal C18 column.

Hello All,

just a quick question regarding particle size and GPC ( or Size Exclusion)columns. I have a sample that needs to be analysed by GPC. The column in question is 5um particle size and 100A pore size. Now, my concern is that the sample to be run contains 2um particles and and i am unsure of the design of GPC columns, would these particles simply pass around the column particles or is it the case that the column particles are that tightly paked the sample would clog the column up?

any info would be appreciated.

Many Thanks

Steve

the problem i have is that i was hoping to analyse the 2um particles so i could do with leaving them in the sample.

Is the frit the guard column? if so if i could get them past the frit would they pass through the column ok?

Jiang, how do i determine the exclusion limit?

Many Thanks

Steve

Respect! You dare to tackle a problem like this yet don´t know that the stat. phase is kept in the column by a porous barrier, normally called a frit.
This whole discussion is of little value if you don´t tell us what the 2 µm particles are.

The column has an inlet frit. Since it is packed with 5 micron particles, the inlet frit is at least 2 micron. I would not want to inject 2 micron particles onto this frit, and I do not recommend to an amatuer to change frits on this column. Plus, 2 micron particles will not migrate through a 5 micron column.

Respect! You dare to tackle a problem like this yet don´t know that the stat. phase is kept in the column by a porous barrier, normally called a frit.

nope, i didnt but i do now. the reason i posted was to learn these facts from experienced analysts such as yourselves

the particle in question is an encapsulated lipid and i am trying to monitor the levels of the encapsulated particles to dtermine how effective my method is to extract the lipid. i thought given the size issues GPC might be a possible way forward, but based on the frit issue this idea seems like a no starter.

Thanks for all the advice though

Steve

There are apparently some people who shoot whole blood unto columns, what I saw was probably internal reverse phase exclusion. So somebody may have a specialty column for part of your problem. I doubt one can do this very well in one step if the molecules to be separated by SEC are much smaller.
Filtering and SPE might help.

Hi Steve,
You might find this concept interesting:
http://www.cohesivetech.com/technologie ... /index.asp
Best Regards