A Shock to the System

After all the vineyards, fermentation tanks, and cellars we have seen on this trip, I witnessed a truly electric lab presentation on wine. Dr. Corsini and her research group are part of an electrochemical lab at San Miniato. They pass electric currents through solutions to measure their metal content. During this particular experiment, Dr. Corsini was measuring the amount of copper in wine.

The first part of the experiment involves electrochemical stripping. This procedure can analyze many elements at a time, detect very minute amounts of metals, and is inexpensive to perform. They first start by taking 4 mL of wine and diluting it with 6 mL of a buffer which helps stabilize the pH of the solution. They then insert three electrodes into the solution: an auxillary, a working, and a reference. Next, they use a computer to set the amount and rate of current that will pass through the wine. After that, nitrogen gas is added while the solution is stirred to aid in the chemical reaction. Finally, the electricity runs through the system and the computer records the results.

During this reaction, the analyte (copper) is deposited onto the surface of the working electrode which has a strip of mercury inside. Later, this analyte is "stripped" off the electrode and the signal received determines the amount of copper present in the solution. After these two steps, the graph will ideally look like the head of a duck such as the one pictured below. The graph we saw did not have this shape however because wine is made up of many different substances, not just copper.




Overall, this experiment was really interesting and informational. I did not know very much about electrochemistry, but I came out of this lab knowing a great deal. Plus, Dr. Corsini geared this experiment toward what we were learning which was very helpful. I hope this lab will spark your interest too.