The latest issue of "California", the magazine of the UC Berkeley alumni
association, has a short article:

Carbon clues, written by Heather Smith.

The article mentions the work of Prof Todd Dawson, who uses a mass spectrometer
to analyze the source of chemicals (and foods/water). Anyway, the article
mentions that:

* the instructor has his students analyze bottled water that is supposedly from
Fiji -- turns out the isotope ratio of the water indicates a western North
American source. [Fake Fiji water.]
* the instrument was used on student vegetarians, to see if they were really
vegetarian. Results: not always; fake veggies.
* the instructor has used the instrument to determine how much of his Carbon is
corn-based (a lot).

Interesting!

Tom Billings