Chromatography Forum

Hello, this will be my 1st post.

Background:
I am developing a PAH quantitationmethod for CG-MS in samples other than water. So a relatively simple 2-phase and evaporation extraction is not really an option.
After centrifugation, 2-phase, filtration, evaporation, I still have some solids in my sample.
I tried filtration over milliporefilters (2x), but they don't work properly due my solvent (CH2Cl2). The next day I found they were molten.

Question:
Are there milliporefilters available that do not dissolve in Dichloromethane?

I hope you can help.
LG

Are you using just a filter membrane, syringe filter, or filter with housing? You might check a Millipore (or other filter supplier) catalog for solvent compatibility diagrams. Teflon (PTFE) membranes should be resistant, but there may be others more suitable for your use. If you are trying to use a membrane in a plastic housing, that will be more difficult as most of the housing materials I am aware of are not suitable.

I employed membrane in plastic housing, plus plastic syringe.

After appliing much pressure, the membrane seems to 'give' and filtrate is still not clear. (Finding the membrane housings molten in my wastebasket did not increase my confidence in proper filtration!)

I'll check the sites of our suppliers and post my findings.


Edit:
http://www.millipore.com/publications.n ... /tb025en00
Millipore supplies filters esp. suited for HPLC (or GC).
Millex filters have low extractables due to HDPE housings,
membranes are available for various purposes and solvents.

Contraintuitively, for my purposes and solvent(s) the Hydrophylic LCR-PTFE membrane is best suited. I would have guessed the hydrophobic or glassfiber filters would be most compatible.

I would suggest the use of glass syringes, swinny filter housings and PTFE membranes. They are a chore to use, but with all glass, stainless steel and PTFE materials, you should be okay.