We analyzed some plastic cups for an isotope class I teach. They included Polyethylene Terephthalate (PETE) Polystyrene (PS) and a third made by Greenware who make their cups from corn. There was no N in any of them - here are the data: Sample %C %N C/N δ13C ‰ δ15N ‰ PETE 62.6 0.0 -27.0 no N peak PS 92.6 0.0 -29.2 no N peak GW 73.2 0.0 -16.0 no N peak Cheers Dave ______________________________________________________________________ David P. Gillikin, Ph.D. Visiting Assistant Professor of Earth Science and Research Associate Department of Earth Science and Geography Vassar College Box 475 Poughkeepsie, NY 12604 phone: 845-437-5545 main office: 845-437-5540 fax: 845-437-7577 email: [log in to unmask] web: http://faculty.vassar.edu/dagillikin/ ______________________________________________________________________ ----- Original Message ----- From: "jay Brandes" <[log in to unmask]> To: [log in to unmask] Sent: Monday, March 29, 2010 4:21:40 PM GMT -05:00 US/Canada Eastern Subject: [ISOGEOCHEM] plastic isotope values Does anyone have a good reference for typical C (and maybe H and N) isotope values for plastics? Thanks-Jay Brandes