Ken,
You have several choices besides isotech
1. Aldrich 32,987-8 water-18^O, normlzed, 95%, 250mg $154.60
2. Oak Ridge National Laboratory
O-18 $160.00 per gram of Oxygen, As Water, 80% - 85% Oxygen-18
http://www.ornl.gov/isotopes/
with this source you will need to do some purification
3. Fluka 1g, $425
With all sources, there will be some/many weeks of delay.
Good luck,
Paul
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Paul T. Jedrzejewski, Ph.D.
Barnett Institute
341 Mugar Bldg.
Northeastern University
360 Huntington Ave.
Boston, MA 02115
phone: 617.373.2857
fax: 617.373.2855 http://www.barnett.neu.edu
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