Chromatography Forum

Hi guys. Can some one tell me what is the the difference between and what each one used for (I mean what kind of solvents I can put in them):
Vial Caps PTFE/SIL, PTFE/RUB, and PTFE/BUTYL-RUBBER.

Vial Caps PTFE/SIL, teflon coated silicone rubber septa lined caps


PTFE/RUB, teflon coated rubber septa caps


and


PTFE/BUTYL-RUBBER.

teflon coated butyl rubber

The cap septa/liners (all are coated with a thin layer of teflon) will absorb solvents that permeate the teflon (chlorinated and aromatic solvents lead the way)

Plasticizers from the different rubber compositions (#2 is unknown) can elute through the teflon if enough time is allowed.

best wishes,

Rod

[quote="chromatographer1"]Vial Caps PTFE/SIL, teflon coated silicone rubber septa lined caps


PTFE/RUB, teflon coated rubber septa caps


and


PTFE/BUTYL-RUBBER.

teflon coated butyl rubber

The cap septa/liners (all are coated with a thin layer of teflon) will absorb solvents that permeate the teflon (chlorinated and aromatic solvents lead the way)

Plasticizers from the different rubber compositions (#2 is unknown) can elute through the teflon if enough time is allowed.

best wishes,

Rod[ Rod, which is the most safe and general use type is it PTFE/SIL?]

For single needle penetration, and for general use, I prefer the silicone rubber with Teflon coating.

But if there weren't applications for the others they would not sell them.

Just remember, with heat, all rubber loses plasticizers and/or eliminates chemicals from itself.

Teflon is permeable, unless it is several hundred meters thick. (this is a joke for those who are unaware, but a joke with a lesson.)

Let the user beware.

But saving money on vial caps was never a good investment. Buy quality or don't bother.

best wishes,

Rod

Didn't someone do a comparison of the various cap liners ? This was several years ago I think and if memory serves they found that the lowest level of contaminants came from the cheapest caps, which were lined with cork faced with aluminium foil.

Peter

AS long as you don't have chlorinated solvents with the aluminum foil, they should work great, Peter.

Aluminum foil is not very permeable, but it is reactive with the right catalyst and the right chemical.

But your comment does not surprise me. If I were doing simple alcohols and ketone type solvents I would not hesitate to use foil lined caps. In fact, I have used them in the past quite successfully.

Peter, are you ready for a warm Summer? We have had a beautifully warm autumn in the Ozarks of Missouri, USA.

One of the nicest I can remember. I wonder what the winter will bring?

Rod

Hello Rod

Daytime temperatures have already reached above 40C here, and will not drop until the rain starts - any day now, as people have been saying for the past two weeks !. We use foil liners on all our sample containers - with some wild dog urine samples the ammonia levels are high enough to discolour the aluminium, but that is a lesser evil than the contamination that comes from elastomer seals.

Peter

Hi Peter,

Wow! It must be exciting working there.. I heard about somewhere thereabouts that they are isolating the compounds in wild dog urine that is the territory markers and they are now going to use those compounds to mark the camps of livestock, so that wild dogs don't go into the camps?

Is that what you guys are doing?



Proof that science can be used in any imaginable part or industry in the world...

Hi Peter,

Wow! It must be exciting working there.. I heard about somewhere thereabouts that they are isolating the compounds in wild dog urine that is the territory markers and they are now going to use those compounds to mark the camps of livestock, so that wild dogs don't go into the camps?

Is that what you guys are doing?



Proof that science can be used in any imaginable part or industry in the world...

Hi Cynthia

Yes, that's us. The grapevine seems to be growing faster than the science though - we are still in the processof identifying the compounds that send the territorial "Keep out" signal, so we are a while away from actually creating artificial territory borders.

Check out www.bpctrust.org for more details, last year there was a piece on the Restek website, and I'll be talking at Analitika in December.

Peter

Peter,

Wow! I get as excited over science as a little girl over a brand new doll!

Well, best of luck to you and your colleagues on identifying and synthesizing the compounds! Maybe I will contact you when I get my PhD (Hopefully end of next year) about some post-doc research opportunities there!

Cindy

Peter that's awesome! I would love to get into something like that...well maybe not urine, but you know what I mean.

Would that be a pheromone, or just some compound that keeps most other animals away?