Saturday, March 3, 2007

SPME...the endgame... finally!!

OK, I realize I've been talking about this for too long. On the 3 month anniversary of the 3rd day after I started this blog (depending on timezone), I am publishing some SPME GC/MS data. This is from an old post, but I am now publishing the computer generated results. First, here is the GC trace:



Second, here are the results...... WAIT JUST A FREAKIN' MINUTE. Before you blindly read and accept the results, I must tell you, these were picked out of an Agilent library based on comparison to MS fragmentation patterns. If Rosko and Derek have taught us anything, it's that computers cannot be trusted. They are very useful, but not infallible ("I'm sorry Dave, I'm afraid I can't do that"). Regardless, let's blindly accept the data from the computer, shall we?

Here it is:


I've only picked a few of the big peaks. However, there are really no surprises. A lot of esters and higher alcohols. The SPME conditions have NOT been optimized. I have not experimented with any other fibers. I'm sure I could mess around with the conditions and find other interesting compounds.

I'd like to look for hop compounds and polyphenols (tannins). I know I'm not the first one to do this, so I'll keep looking for information related to this.

Until then, realize as you drink your beer: what a wonderful chemical concoction it is.

4 comments:

TotallyMedicinal said...

Do you not think you'd be better off with LC-MS for those polyphenols? Some of them (especially the dimeric ones) have pretty high molecular weights and probably won't fly that well in GC.

On the beer front, I am very lucky as my partner is German, so I spend a good amount of time in southern Germany enjoying the fruits of the Rheinheitsgebot, and am especially fond of Erdinger Duckleshefeweise

Chemgeek said...

I'd love to do LC-MS, but alas, I don't have it at my disposal. I plan on doing HPLC (UV detector) sometime.
Enjoy the good beer. I envy you.

Tracy P. Hamilton said...

Here is a web page for a paper that uses HPLC to test for the six iso alpha acids (three, cis and trans)- it is free!

http://www.scientificsocieties.org/jib/abstracts/2004/G-2004-0310-213.htm

Woller's Disciples said...

The hop characteristics sounds like a good research project for a lucky student.