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Dear Uli,

see following articles. You can buy natural caffeine from e.g. Coffein
Compagnie, Bremen, Germany. Best regards

Roland

Danho et al. (1992): Deuterium, carbon and nitrogen isotopic analysis of
natural and synthetic caffeine - Authentification of coffees and coffee
extracts. Analusis 20: (3) 179-184.  ((intramolecular) d2H, d13C, d15N)

Dunbar and Wilson (1982): Determination of geographic origin of caffeine
by stable isotope analysis. Anal. Chem. 54, 590-592.   (d13C, d18O, d2H)

Weilacher et al. (1996): Carbon isotope pattern in purine alkaloids. A
key to isotope discriminations in C1 compounds. Phytochem 41,
1073-1077.   ((intramolecular) d13C,
d15N)

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Dr. Roland A. Werner
Max-Planck-Institut fuer Biogeochemie
Carl-Zeiss-Promenade 10, 07745 Jena, Germany
Postanschrift:
Postfach 10 01 64, 07701 Jena, Germany
Tel.: +49-3641-643719, -643825
Fax:  +49-3641-643710
e-mail: [log in to unmask]

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