[Solemn]

I'm trying to see how much ethanol is produced by yeast cells on YPD. Being able to add a single reagent to produce a visible reaction would be ideal. Effervescence, a visible color change, or a change in turbidity would be good. Just something that would allow me to show more or less ethanol present in different agar mediums. I've only found one option so far, being Potassium Dichromate, but it looks like it would require a lot of work to set up (possibly using titration?), which I am trying to avoid. Lucas' reagent wouldn't work because I am only looking for ethanol to be present, which produces no visible reaction with Lucas' reagent.

Any suggestions?

[Arkcon]

We were thinking about it over here: http://www.chemicalforums.com/index.php?topic=62706.msg224286#msg224286  but no one's come up with a simple  assay for alcohol.

[sagar]

Hello,
We cannot exactly say how much but i think at least 40% must be produced...

[Arkcon]

Hello,
We cannot exactly say how much but i think at least 40% must be produced...

I don't know how you can be so quantitative, given that you don't have the sample before you, unless Solemn: sent it to you via TCP/IP.  However, your response is simply incorrect, only in very rare circumstances can yeast produce alcohol content above 12-16 %, greater than that is too toxic, and the fermentation slows.  This of course, adds even more difficultly to the O.P.'s question, they're looking for a wet chemistry reaction, that can measure only slight differences, that's asking a lot.  The other thread on this topic has better ideas.

[Yggdrasil]

I wonder if you could do some sort of electrochemical analysis on the vapor above the agar (i.e. a breathalyzer test).