The discussion about O-18 water has taken me back to my first
graduate project, which involved labelling phosphate groups with
oxygen isotopes. I won't bore anyone with why we were doing this...
Anyway, back then one could get O-18 water direct from the source:
Oak Ridge Nat. Labs
After one minute on the web I discovered that this is still true.
Check out : http://www.ornl.gov/isotopes/
Current price is $160/per gram of oxygen, as 85% isotopically pure
O18-water. Back in grad school it was $60 a gram. Oh well, your
tax dollars at work.
Elliott Nickbarg
Genetics Inst. Inc.