I have an unopened 50 gram sample of O-18 water that is left over from a Bio-Medical Lab that was set-up in the 90s. The sample is normalized to 98.9% O-18 and was produced by Isotec. Please contact me for more info if you have an interest in this material. Regards, Clay Clay Herzog Herzog Design Engineering 109 E Chapline St. Sharpsburg, MD 21782 301-432-5682 (home) 717-977-1043 (mobile) [log in to unmask]