Perspectives and Future Aspects

Isotope ratio measurements entered quality control of flavouring compounds about 20 years ago, and today this methodology has been established as a routine test in a number of laboratories. The special field and the potential for isotope analysis is authenticity identification of flavourings and their components, mainly with regard to the differentiation between natural and nature-identical or synthetic products and to their assignment to botanical and climatic origins. To this end isotope analysis completes and enlarges the quality information provided by classic methods. 

With this in mind this contribution has tried to show the state of the art and to outline the potential, but also the limits of the methods available and the information to be obtained. This will be of advantage and importance for producers, dealers and consumers, but also for adulterators, in so far as the latter try to conceive more and more sophisticated ways of blending. This in turn demands the adaptation and further development of the analytical methods. We believe that this will mainly concern methods which lead to the elucidation of inter- and intramolecular isotopic patterns, which will not and cannot be imitated, not only from a technical but also from a financial point of view. A very important progress of the last five years is that we have learned to understand and use the systematics of the isotopic patterns of natural compounds. 

Without any doubt the most valuable development in mass spectrometry has been multi-compound/multi-isotope analysis. This implies the application of GC-C/P-IRMS to the on-line analysis, not only of carbon but also of other isotopes, preferably of hydrogen and oxygen, in the individual components of a mixture, and the use of the metabolic and isotopic correlations obtained from such an analysis. In the course of this chapter, the potential of (positional) oxygen isotope analysis has been emphasised several times and this will still be a challenge of the future. The advantage of GC-C/ P-IRMS is its speed in performance and the very moderate demand on sample size and purity, and also its implication for automation. The information available can easily be correlated to that of other (classic) analyses. However, a disadvantage will be always that the data concern a global mean value for the whole molecule in question. 

Schmidt, H. Forstel, K. Heinzinger (eds.) Stable Isotopes. Proc. 4 Int. Conf., Elsevier Scientific Publishing Company, Amsterdam, pp. 483-493 

Balabane, R. LetoUe, J.-C. Bayle, M. Derbesy (1983) Determination du rapport et H/ 

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