Translated abstract:
The stable isotope ratio determination of bio-elements serves, mainly as multi-element analysis, for the identification of the origin and the authenticity of food commodities. A prototype of a device for the simultaneous isotope analysis of C, H , N and S in a single sample could successfully be tested, and the reductive pyrolytic determination of the δ18O-value of N-containing samples could be enhanced. The positional 18O-analysis of the p-OH-group L-tyrosine from proteins of vegetarian animals permitted the proof, whether these had received animal products in their feed. An S-isotope analysis on sulphate and organic S in defined fractions from vegetal and animal nutrients showed that only the global δ34S-value is suited as a bio-marker for origin identifications.