Submitted by Cameron Gren / University of North Alabama on Thu, 05/16/2019 - 17:43

I work with air-sensitive organometallic compounds When I was in graduate school, we used to send off samples for x-ray crystallography in ampules that we would seal using a little apparatus. It was essntially a screw cap with a hole and an o-ring that you would put around the ampoule. That would then screw onto (I think) a threaded glass adapter with a ground-glass joint on the other end that you would put a gas inlet onto. All of this could be done in the glove box, then brought out and put on the Schlenk line. I seem to remember pulling a slight vacuum before sealing it. I'm guessing this was so the gas inside wouldn't expand and blow the seal out when flame sealing the ampoule.

I have tried to find an apparatus like this to order either intact or piece-by-piece (I have plenty of gas inlets), but I just can't seem to find the glass piece and the screw-down o-ring closure!!! Can anyone help me, please?

Kyle Grice / DePaul University

Hi Cameron,


Here's what I've been using for sealing NMR tubes:

You can also get ampules glass-blown onto 14/20 joints an use that.

A simpler approach would be to use thick rubber tubing between a closable 180 joint and the ampule. Set it up in the glovebox, bring out and then flame seal on the line.


Fri, 05/17/2019 - 10:16 Permalink
Adam Johnson / Harvey Mudd College

the valve you're looking for is a Cajon fitting from Swagelok. A quick search of their website did not turn anything up but you are looking for o-ring fittings. One side of this is correct. The glass piece is usually a ground glass stopcock terminating in 1/4" OD glass.

I actually stumbled on this page becasue I am trying (with little success) to seal my air sensitive samples in ampules using this exact fitting. I literally just got back from Lowe's with a small hand torch for finer control. wish me luck.

Wed, 06/12/2019 - 17:21 Permalink