[SubtleAphex]

I do not have much of an electrochemistry background so I'm looking for some help.  I have conducted an experiment where I bias a potato(russet) in a quadrupole arrangement using gold plated electrodes.  The bias was set as follows: top-left = +9V, top-right = 0V, bottom-left = 0V, bottom-right = +9V in the attached pic.  During this experiment I observed a gas reaction(bubbling) at the 0V electrodes which tended to force them out of the potato.  Is it likely that a redox recation occured at the 0V electrodes?  If so is it possible to identify what that reaction would have been?  In literature I have found a few common redox reactions involving water, oxygen, hydroxide or hydrogen but I'm not sure how to determine which of the reactions is what I was probably observing.  The potato probably has water and hydroxide readily available.  At the +9V electrodes I did not observe a gas reaction.  However I did notice after completion of the experiment that the potato had turned a blue-green color around the electrodes which was darker right next to the metal.  The electrode was a metal pin, plated with gold on top of soft nickel.  I did notice that the gold was partially gone from some of the electrodes after the experiment.  Is it likely that the electrode reaction at the +9V electrodes was Au -> Au3+ + 3e-?  Would you expect Au3+ to be blue-green in a liquid medium?  Are there other reactions I should be considering at both the negative and positivie electrodes? 

[SirRoderick]

Well the easiest way to confirm hydrogen is collecting the gas in a test tube or similar vessel and lighting it. Unmistakable.
As for Au, only time I've seen any in solution was through aqua regia. That was yellow, due to AuCl I believe.

Can't help you at all with the rest I think.

Can I ask why you're doing this?

[SubtleAphex]

Thanks for your reply - I was doing an experiment which analyzed the surface potential in the biased potato.  Do you have suggestions for other online resources(forums, etc) that might be helpful?  I can't seem to find many Electrochemistry or Electrobiology forums.