What is the purple flammable liquid pooling in my cloud chamber?

[Thundagere]

I recently observed a liquid pooling at the bottom of my cloud chamber. It was purple in color and rather odd. It was certainly flammable, which leads me to believe that it was a result of solventing between the supersaturated alcohol and the canned air used for my chamber.
http://imageshack.us/a/img525/7906/20121122131134.th.jpg
I'm not quite sure what it is. I know that it was probably a combination of the Isopropyl alcohol and the difluroethane, but I'm not sure on this. Could anyone help me out?

 

[chemisttree]

Does your cloud chamber have a dark background paper?

 

[Thundagere]

THe one that I was using had the pain spray painted onto it. It was essentially a jar, with a metal top. The sponge was attached to the metal, and the outside bottom of the jar was spray painted black.
Incidentally, I found out that one had air leaks. I made a new one with sheet metal and a plastic box. The purple liquid did not appear.

 

[chemisttree]

Perhaps the purple is something extracted from the sponge.

 

[Thundagere]

But why would it only be extracted from the sponge in an air leak? In the good one, nothing showed up.