[ChemEngStudent]

Hello,
I am a chemical engineering student and we are trying to figure out how to extract aroma without losing any of the compounds so that we can analyze by GCMS. We brewed New England IPA style by using dry hops, yeast, and a Zymatic brewing machine. We are trying to figure out what specific compounds gives the New England IPA the flavor so that we can manipulate the process. We are trying to run Head Space analysis in GCMS (testing the vapor aroma without injecting the beer). Our issue is that as soon as we open the bottle, the aroma gets lost when exposed to air and we are trying to find a mechanism to not lose any aroma. We want to make something homemade and inexpensive so that when we open the bottle all aromas are concentrated and captured. We need ideas of how to make a sealed process to do so if any of you have some suggestions it would be appreciated!

[chinaski]

How about coating the bottle cap in something that might be flexible enough to partially reseal a hole in it (I'm thinking silicon sealant that's been allowed to fully cure).  The drill the smallest possible hole to acommodate a syringe and quickly fit an empty syringe into the hole and pull out the co2 that will be coming out.  Be sure to have the beer cold or you'll definitely get all foam.  You might get a gyser of co2 and foam anyway, but worth a try. 

[narvin]

Not sure about a capped bottle, but you could keg it next time and vent out through the gas in line.  A 2.5 gallon keg isn't that expensive.

[Ariousig]

I don't think 2.5 Gallon would be that expensive.

[goose]

You could also find a local brewery that has a D.O. (dissolved Oxygen) machine and maybe borrow their bottle cap piercing device.  That would allow you to quickly collect the CO2 and other aromatics quickly.  You would have to purge it with CO2 first to remove any oxygen and/or other aromas that might be lingering in the device before using it.
The easiest option would be to use a 2.5 gallon keg and collect the sample through the gas in keg plug, as Ariousig suggested.  There should be enough CO2 and aroma compounds in the head space that will allow you to take multiple samples.
Good luck with your project.  I remember using a GC back in my college chemistry days.  It sometimes haunts me at night many years later!