which column is better for ethylene measurement?

[chromatographer1]

You have to call or email them as they are custom ordered. Supelco has one in its catalog is sells routinely, but it is a Carboxen 1004 column.
Restek also sells them. Supelco sales office in Uruguay:

Dexin Grupo Quimico SRL
Montevideo, Uruguay
Phone: 598 2 507 6616
Fax: 598 2 507 0155
E-mail: dexin@adinet.com.uy
Website: Argentina

[Johnny Rod]

Rod, in reply to your questions earlier (sorry for the delay) re. alumina columns.

I live and learn too, I was unaware how much trouble alumina can cause with unsaturates, in all honesty. We've been using the same column for at least five years, more or less daily, with admittedly dry gas samples, and the performance is still good. I wonder if I asked Agilent how they deactivate it they'd really tell me...

[chromatographer1]

I can tell you how basically it is done (oh my, pardon the pun).

A base is added to the alumina which neutralizes the acidic nature of the beast. Organic or inorganic base is added. Then questions of completeness and eventual loss come into play. Even fused silica itself is reactive to a degree (ever hear of the catalytic presence of metals?).

Now losses of a ng or so usually doesn't give anyone a problem, but if all you have on column is 2ng then accurate measurement is impossible. If you put 1000ng of sample on column then who would even notice such a loss?

If you were an olefin one can slide bare bottom down a tunnel made of slick plastic (porous polymer) or granulated sand (alumina). It is your behind at risk ! Some skin loss is inevitable either way.

We live in an imperfect world and yet we make do.

best wishes,

Rod