got me stumped on Freon 14

[chromatographer1]

Anyone know of a GC column that separates methane from carbon tetrafluoride, Freon 14?

Would Carbowax 1500 work? Gas Pro? 1% SP-1000 on Carbopack B?

I have no information on a proven separation.

Thanks for any help.

Rod

[ted122]

Try a Restek BAC-2 column. Several of the flurocarbons can be separated with this column

[Bruce Hamilton]

It may depends on the concentration. CF4 is routinely analysed as part of the trace emissions from alumium smelters.

If you are working at trace levels I'd look in the literature under tetrafluoromethane, the more common environmental testing name for emissions from wafer fabrication and Al smelters.

Personally, I liked the monitoring option exercised by the smelter neighbours - they planted fluride-sensitive plants, such geraniums.

My recollection was that at trace levels, CF4 was a real pig as regards to binding to sampling systems, unless PTFE lines were used.

The one time I measured it, I had to use a cryogenic molecular sieve packed column ( 4A or 5A ) to separate it from other fluorinated methanes, not sure where methane was, as that was measured separately by FID.

I recall that my packed Carbopak B column didn't resolve methane and CF4, and that somebody had used an alumina column on fluorinated emissions.

I suspect a literature seach on perfluorinated atmospheric pollutants might offer some guidance.

Please keep having fun,

Bruce Hamilton

[chromatographer1]

Thanks, Ted and Bruce.

After thinking about it and especially after reading your post, Bruce, I believe that an alumina column will separate Freon 14 from methane.

I would also suspect that a MS13X or 5A would separate them, especially the 13X. I was asked the question about a reliable separation and could not give a good answer. I would suspect that methane would elute after F-14 on a Carbowax column and possibly as well on a Carbopack B column too.

Now a carnation detector would brighten up the lab, wouldn't it? Sounds like a nice addition to our lab. Thanks, very much for mentioning that one, Bruce.

Alpha cyclodetrin column might also perform the separation, but I lean against it.

If anyone else has a solid proven separation I would still love to learn about it.

Thanks to all.

Rod