Cambridge Isotope Laboratories (Popularity: ): Manufacturer of stable isotope labeled compounds and some fine deuterated solvents too. C/D/N ISOTOPES (Popularity: ): Quite a large listing of deuterated compounds and Carbon-13 and Nitrogen-15 labelled compounds. In English ... Medical Isotopes, Inc. (Popularity: ): Nearly a complete line of enriched biochemicals. Nice selection of fatty acids, enriched with C13.