Chromatography Forum

I have looked in the archives and found that this question has been posted before (in '06) but there were no answers.

We have conducted the EPA 3640 GPC cleanup on sediment samples and have used a Waters Envirogel column. After that one failed we switched to a Jordi Fluorinated DVB column, as it could apparently tollerate acetone but the column did not have the ideal separation.

The sediments are extracted with DCM:Acetone. The Waters GPC column does not like acetone but I thought one could usually get away with 5-10% acetone.

Alternatives are Envirosep ABC column, going back to Waters or a low pressure column. Does anyone have a recommendation? Also, if your sampes were extracted with acetone, do you bring your samples down to dryness or just minimize the % acetone?

Thank you.

First, these systems are not really "GPC" as it is usually practiced for polymer samples, but that is a moot point, since these are standard methods. However, unlike true GPC, the solvent does matter here, as you are probably doing some adsorption chromatography along with the size separation.

As I recall (it's been quite a few years), the system is supposed to use methylene chloride only. These columns are quite "soft" and so a small change in solvent environment could cause them to change their swelling, which might make the column unusable. Also, if you are injecting in a solvent mixture, you may find that some materials are insoluble in all methylene chloride, and so are precipitating on the column.

I would try taking your samples to dryness or almost dryness, and then dissolving in all methylene chloride. Filter and try injecting again.

EBChemist,

Using an HPLC or a low pressure pump? I have built a couple of these for environmental labs but they all used low pressure pumps since you don't want to squish the recommended gel too much. The ones I built used Bio-Rad beads (been a while but I can probably find the folder....)

Best regards,

AICMM