Chemistry Forum

I am having a rough time here.
Where to begin. I am trying to filter the product Captex 200. This is propylene glycol dicaprylic/dicapric. I need to get this product sterile so I purchased some Nalgene bottletop filters .22 micron Nylon membrane, this compound melts the polystyrene housing and the filtrate comes out cloudy and pinkish. So we went with another route Whatman PVDF syringe filters .22 micron but this compound will sort of melt these too. Some of the filtrate comes out clear and looks fine but after about 40ml the filter clogs and becomes impossible. Plus 40ml is a small fraction of what needs to be filtered. I need to get 1liter filtered in a reasonable amount of time with vacuum.
The compound calls for resistance to HDPE and polypropylene.
Does anyone here have experience with filter types and media types that will handle this load???
Thanks in advance.

I recommend this assembly
http://tinyurl.com/79yvuas

with PFTE disc filters of corresponding size
http://www.sigmaaldrich.com/labware/lab ... e=21720976

Thank you so much for the response. I don't know if I mentioned but the specs on the product claim that it should not be stored in ..... Well I'll just copy and paste it here:

8. Packaging instructions
MIGLYOL neutral oils are good solvents, like other low-viscosity polar ester oils. Some plastics, especially those containing plastisizers, can become brittle or expand. Polystyrene and PVC are not suitable.
Be careful when selecting resistant-seal closure material (e.g., VITON), and be careful of sufficient pull power because MIGLYOL neutral oils have a high tendency to migrate.
The following packaging materials are recommended:
- Low pressure polyethylene (High Density PE = HDPE)
- Polypropylene
- Metal (aluminium)
- Glass
Sasol

So as you can see there is Polypropylene and HDPE that are safe with it. I found a company that offers filters that have a polypropylene MEMBRANE. So are you positive that a PTFE membrane will do the trick???

Thanks in advance, I will request samples of the membranes and purchase the apparatus.

PFTE stands for Polytetrafluoroethylene or Teflon
http://en.wikipedia.org/wiki/Polytetrafluoroethylene

There are things that dissolve gold and still not even etch teflon. Your formulations will certainly be compatible with PTFE, but HDPE is cheaper, and it's OK too and cheaper. HDPE maybe a better choice if you concern about the cost.
The funnel that I recommended is made of glass, so it's OK too.

Doesn't look like my reply is going in. So here goes again.
Thanks for the advise. HDPE is not an option of media in the site you referred me to just PES PVDF and a few others I'm not familiar with. So it looks like the Teflon is what we will try.
Question:
Do you think the company will send us a sample to test before we have to purchase something that may or may not work???

Aldrich is a resellar, so they don't have an incetive with samples. Just buy a smallest pack of PFTE filters. Filter disks are not as expensive as filter assembly. It's a high chance that they will work, just make sure buy the right size.

Thanks for all your help. We are making a purchase of these Mon.

If the PFTE doesn't work for you give us a call. We're a manufacturer of both filter media and filtration equipment. Our chemical sales manager is Bill Kearney. www.ertelalsop.com